Changes to Accommodate Xcode 5 DP and A Few Tests

Hey @matbd,

I have made some changes to the code in order to accommodate Xcode 5 Developer Preview, with which the emitted pth file extension has been changed to .pch.pch.

Along with the changes, I have added a few tests.

Please help review my changes, and add tests you have in mind.

Look forward to your pull request to oclint/oclint-xcodebuild. Thank you.