Added/removed missing links and ProtoBuf support

Removed:

- link to EndpointType.cs in ServiceStack.Common
- link to ServiceAttribute.cs in ServiceStack.Interfaces

Added protobuf support for Android:

- protobuf-net.dll compiled as Android library
- new project ServiceStack.Plugins.ProtoBuf.Android.csproj
Created Windows Phone 8 solution

Windows Phone (7.1) solution copied and modified to support Windows
Phone 8.
Removed missing file link from WP7.1