Added VS2013 (RC) test project

Hi Phil,
It looks like the pull request is for a branch, not for a commit. So 3 commits

1. I've created an upgraded test project for VS2013(RC).
2. Eliminated std::string objects that hold constant strings, and reverted to char const*. This helps step-debugging in MSVC where "step-into" a CHECK (for example) steps into several ctors and dtor for creation/destruction of temporaries.
3. Generated single include

The second commit made a change to catch_expressionresult_builder.hpp(93) but I can't find a test for thiscode path so it is untested. I fairly sure it code does the same thing though!
 
Cheers
Craig