Merge pull request #299 from sanjeevdwivedi/master

Added  solutions for WP8.1 Silverlight and NetFX core and updated the jakefile
updated SimpleJson to v0.38.0
Merge pull request #301 from facebook-csharp-sdk/simplejson-v0-38-0

updated SimpleJson to v0.38.0
updated version to v6.5.0
Adding the missing file for GetLoginUrl and ParseOAuthCallbackUrl