THRIFT-160. csharp: Created THttpTransport for the C# library based on WebHttpRequest

This patch adds a new THttpTransport to the C# library and adds some related changes to the Makefile and csproj.

Patch: Michael Greene and Todd Gardner

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@957708 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/csharp/Makefile.am b/lib/csharp/Makefile.am
index 039db74..d8a007b 100644
--- a/lib/csharp/Makefile.am
+++ b/lib/csharp/Makefile.am
@@ -46,6 +46,7 @@
             src/Transport/TServerTransport.cs \
             src/Transport/TServerSocket.cs \
             src/Transport/TTransportFactory.cs \
+            src/Transport/THttpClient.cs \
             src/TProcessor.cs \
             src/TApplicationException.cs