docs: add cloud backends from blog

Documentation/gce-backend.md

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+# GCE Backend for Flannel
+
+From the Developers Console, we start by creating a new network.
+
+Configure the network name and address range. Then add firewall rules to allow etcd traffic (tcp/2379), SSH, and ICMP. 
+That's it for the network configuration.
+Now it’s time to create an instance.
+Let's call it `demo-instance-1`.
+Under the "Management, disk, networking, access & security options" make the following changes:
+
+- Select the "Network" to be our newly created network
+- Enable IP forwarding
+- Under "Access and Security" set the compute permissions to "Read Write" and remember to add your SSH key
+
+<br/>
+<div class="row">
+  <div class="col-lg-6 col-md-6 col-sm-6 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/gce-instance.png">
+      <img src="{{site.baseurl}}/assets/images/media/gce-instance.png" alt="New GCE Instance">
+    </a>
+    <div class="co-m-screenshot-caption">Booting a new GCE instance</div>
+  </div>
+  <div class="col-lg-6 col-md-6 col-sm-6 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/gce-instance-and-security.png">
+      <img src="{{site.baseurl}}/assets/images/media/gce-instance-and-security.png" alt="Security settings for a new instance">
+    </a>
+    <div class="co-m-screenshot-caption">Security settings for a new instance</div>
+  </div>
+</div>
+
+With the permissions set, we can launch the instance! 
+
+The only remaining steps now are to start etcd, publish the network configuration and lastly, run the flannel daemon. 
+SSH into `demo-instance-1` and execute the following steps:
+
+- Start etcd:
+
+```
+$ etcd2 -advertise-client-urls http://$INTERNAL_IP:2379 -listen-client-urls http://0.0.0.0:2379
+```
+
+- Publish configuration in etcd (ensure that the network range does not overlap with the one configured for the GCE network)
+
+```
+$ etcdctl set /coreos.com/network/config '{"Network":"10.40.0.0/16", "Backend": {"Type": "gce"}}'
+```
+
+- Fetch the 0.5 release using wget from [here](https://github.com/coreos/flannel/releases/download/v0.5.0/flannel-0.5.0-linux-amd64.tar.gz)
+- Run flannel daemon:
+
+```
+$ sudo ./flanneld --etcd-endpoints=http://127.0.0.1:2379
+```
+
+Now make a clone of `demo-instance-1` and SSH into it to run the these steps:
+
+- Fetch the 0.5 release as before.
+- Run flannel with the `--etcd-endpoints` flag set to the *internal* IP of the instance running etcd
+
+Check that the subnet lease acquired by each of the hosts has been added!
+
+<br/>
+<div class="row">
+  <div class="col-lg-10 col-lg-offset-1 col-md-10 col-md-offset-1 col-sm-12 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/gce-routes.png" class="co-m-screenshot">
+      <img src="{{site.baseurl}}/assets/images/media/gce-routes.png" alt="GCE Routes" />
+    </a>
+  </div>
+</div>
+<div class="caption">GCE Routes</div>
+
+It’s important to note that GCE currently [limits](https://cloud.google.com/compute/docs/resource-quotas) the number of routes per *project* to 100. 

Documentation/vpc-backend.md

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+# Amazon VPC Backend for Flannel
+
+In order to run flannel on AWS we need to first create an [Amazon VPC](http://aws.amazon.com/vpc/).
+Amazon VPC enables us to launch EC2 instances into a virtual network, which we can configure via its route table.
+
+From the VPC dashboard start out by running the "VPC Wizard":
+
+- Select "VPC with a Single Public Subnet"
+- Configure the network and the subnet address ranges 
+
+<br/>
+<div class="row">
+  <div class="col-lg-10 col-lg-offset-1 col-md-10 col-md-offset-1 col-sm-12 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/aws-vpc.png">
+      <img src="{{site.baseurl}}/assets/images/media/aws-vpc.png" alt="New Amazon VPC" />
+    </a>
+  </div>
+</div>
+<div class="caption">Creating a new Amazon VPC</div>
+
+Now that we have set up our VPC and subnet, let’s create an Identity and Access Management ([IAM](http://aws.amazon.com/iam/)) role to grant the required permissions to our EC2 instances. 
+
+From the console, select Services -> Administration & Security -> IAM. 
+
+We first need to create a [policy](http://docs.aws.amazon.com/IAM/latest/UserGuide/policies_overview.html) that we will later assign to an IAM role.
+Under "Create Policy" select the "Create Your Own Policy" option.
+The following permissions are required as shown below in the sample policy document.
+
+- ec2:CreateRoute
+- ec2:DeleteRoute
+- ec2:ReplaceRoute
+- ec2:DescribeRouteTables
+- ec2:DescribeInstances
+
+```
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+          "Effect": "Allow",
+          "Action": [
+              "ec2:CreateRoute",
+              "ec2:DeleteRoute",
+              "ec2:ReplaceRoute"
+          ],
+          "Resource": [
+              "*"
+          ]
+    },
+    {
+          "Effect": "Allow",
+          "Action": [
+              "ec2:DescribeRouteTables",
+              "ec2:DescribeInstances"
+          ],
+          "Resource": "*"
+    }
+  ]
+}
+```
+
+Note that although the first three permissions can be tied to the route table resource of our subnet, the ec2:Describe\* permissions can not be limited to a particular resource.
+For simplicity, we leave the "Resource" as wildcard in both. 
+
+With the policy added, let's attach it to a new IAM role by clicking the "Create New Role" button and setting the following options:
+
+- Role Name: `demo-role`
+- Role Type: "Amazon EC2"
+- Attach the policy we created earlier
+
+We are now all set to launch an EC2 instance. 
+In the launch wizard, choose the `CoreOS-stable-681.2.0` image and under "Configure Instance Details" perform the following steps:
+
+- Change the "Network" to the VPC we just created
+- Enable "Auto-assign Public IP"
+- Select IAM `demo-role`
+
+<br/>
+<div class="row">
+  <div class="col-lg-10 col-lg-offset-1 col-md-10 col-md-offset-1 col-sm-12 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/aws-instance-configuration.png" class="co-m-screenshot">
+      <img src="{{site.baseurl}}/assets/images/media/aws-instance-configuration.png" alt="AWS EC2 Instance Details" />
+    </a>
+  </div>
+</div>
+<div class="caption">Configuring AWS EC2 instance details</div>
+
+Under the "Configure Security Group" tab add the rules to allow etcd traffic (tcp/2379), SSH and ICMP.
+
+Go ahead and launch the instance! 
+
+Since our instance will be sending and receiving traffic for IPs other than the one assigned by our subnet, we need to disable source/destination checks. 
+
+<br/>
+<div class="row">
+  <div class="col-lg-10 col-lg-offset-1 col-md-10 col-md-offset-1 col-sm-12 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/aws-src-dst-check.png" class="co-m-screenshot">
+      <img src="{{site.baseurl}}/assets/images/media/aws-src-dst-check.png" alt="Disable AWS Source/Dest Check" />
+    </a>
+  </div>
+</div>
+<div class="caption">Disable AWS Source/Dest Check</div>
+
+All that’s left now is to start etcd, publish the network configuration and run the flannel daemon. 
+First, SSH into `demo-instance-1`:
+
+- Start etcd:
+
+```
+$ etcd2 -advertise-client-urls http://$INTERNAL_IP:2379 -listen-client-urls http://0.0.0.0:2379
+```
+- Publish configuration in etcd (ensure that the network range does not overlap with the one configured for the VPC)
+
+```
+$ etcdctl set /coreos.com/network/config '{"Network":"10.20.0.0/16", "Backend": {"Type": "aws-vpc"}}'
+```
+- Fetch the latest release using wget from [here](https://github.com/coreos/flannel/releases/download/v0.5.0/flannel-0.5.0-linux-amd64.tar.gz)
+- Run flannel daemon:
+
+```
+sudo ./flanneld --etcd-endpoints=http://127.0.0.1:2379
+```
+
+Next, create and connect to a clone of `demo-instance-1`.
+Run flannel with the `--etcd-endpoints` flag set to the *internal* IP of the instance running etcd.
+
+Confirm that the subnet route table has entries for the lease acquired by each of the subnets.
+
+<br/>
+<div class="row">
+  <div class="col-lg-10 col-lg-offset-1 col-md-10 col-md-offset-1 col-sm-12 col-xs-12 co-m-screenshot">
+    <a href="{{site.baseurl}}/assets/images/media/aws-routes.png" class="co-m-screenshot">
+      <img src="{{site.baseurl}}/assets/images/media/aws-routes.png" alt="AWS Routes" />
+    </a>
+  </div>
+</div>
+<div class="caption">AWS Routes</div>
+
+Keep in mind that the Amazon VPC [limits](http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Appendix_Limits.html) the number of entries per route table to 50.