Initial MEF removal

The code base no longer requires MEF in order to function.  All
interesting types are available directly through EditorUtilsFactory.
Lots of cleanup left but the main work is complete
Cleaned up the code a bit

Added some tests to ensure that MEF is never used
Removed more MEF leftovers

Removed the EditorUtilsVsix project which existed solely to support MEF.
Also Cleaned up the projects which are used to ad-hoc test the
EditorUtils DLL
Version number update
Fixed inheritance interface
Made the caching configurable in the derived types
Removed powershell files

Since it's no longer a MEF component there is no longer a need to test
the registration. Removing it from the scripts
Merge pull request #1 from jaredpar/bugs-no-mef

Remove MEF usage