Adds static global property to emulate building inside Visual Studio.
Remove DevEnv test support.
Retargeted from MSBuild v4.0 to MSBuild v12.

This reflects the actual MSBuild that NuProj in VS targets.
Reinstalled NuGet packages with the new target framework.
Testing no longer blocks thread during NuGet package restore.
Merge Kovalikp's changes.
Merge pull request #2 from AArnott/tests

Add VS emulation support