[VS Addin] Add visual studio 2012 support

Basic support for running and debugging of nacl and ppapi
module is working.  The two major problem are the lack
of unit tests and the fact that nacl targets are always
seen as dirty by VS2012 and will always completely rebuild.

TEST=test.bat (+ manual testing for 2012)

Review URL: https://codereview.chromium.org/14122017

git-svn-id: https://nativeclient-sdk.googlecode.com/svn/trunk/src@1554 050acbb0-2703-11df-ab0a-9f3f633ae91d
48 files changed