Support latest FirefoxDeveloperEdition.app without spaces (#280)

Latest version of Firefox Developer Edition on macOS seem to use
upper camel case naming for the app. This ensures that the CA will
be added to the Firefox trust store if using recent versions of
FF Dev Edition.

truststore_nss.go

@@ -28,6 +28,7 @@ var (
 		"/usr/bin/firefox-nightly",
 		"/usr/bin/firefox-developer-edition",
 		"/Applications/Firefox.app",
+		"/Applications/FirefoxDeveloperEdition.app",
 		"/Applications/Firefox Developer Edition.app",
 		"/Applications/Firefox Nightly.app",
 		"C:\\Program Files\\Mozilla Firefox",