Updated Nuget Package, WinRT, and Async & Await Support (Net45)

Created a WinRT universal class library version.
Created a .Net 4.5 version
Async/Await support for WinRT and Net 4.5.
*** Note, WinRT project requires VS2013, WP 7.x/SL4 require VS2012, so there are separate solutions *** 

Reinstated some (async) auth/token methods for WP/SL.
Includes latest code from main repository, including 64 bit id fixes etc.
Aligned hammock project names with tweetsharp solution references.
Rebuilt all projects in release mode and updated nuget package, with new version number. 
Nuget package also specifies newer json.net package dependency, 5.08 for WP/SL and 6.04 for other projects.