Added support for compiling against .NET 4.5
Removed comments from last commit (should have been removed then, was only for testing).
IronPython compiling agains v4.5

Pull #85
"Everything" compiles
Renamed to FEATURE_
Update IronPython.sln with the v45{Debug,Release} targets.
Win8 changes

cherry picked from 4960eb5ff6132e4b950230a6158bba3026ad2d5f
Enable building v45{Release,Debug}.
Disable Android builds, as they are hopelessly broken right now.

They were experimental anyway.
Fix a test based on a string that changed in .NET 4.