Upgrade solution to .NET4.5 and VS 2012

Upgraded solution to Visual Studio 2012 and .NET 4.5. VS 2010 and earlier does not support .NET 4.5.
Updated nuget packages.config files to reference net45 versions of EF5.
Updated references to net45 version of EF5 dll in packages folder.

Note:
This converts the entire solution to .net 4.5.
I suppose you would like to maintain one version of FakeDbSet for .net 4.0, but I don't know what your plans are for this so I did not take that into account.