Prefer VS2013 where possible
Added 409 conflict when trying to create projection with existing name (instead of 500)
Fix project file
Make build script Mac-friendly

- Set the DLYD_LIBRARY_PATH when building V8 such that building the
  snapshot doesn't fail
- Use appropriate extensions for shared libraries when copying etc
  (dylib for Mac OS, so for Linux)
- Set appropriate dylib install names if on Mac OS. There may be a
  better way to do that during the build of V8 but Gyp.
Fix typo which environment vars cunningly mask
Add Mac to the appropriate section of the README
Pulled from upstream