Updated PySide build.

- Fixed PySide build commands to work with latest PySide release on OS X.
- Fixed PySide license installation.
- Fixed Gaffer.About.dependencies() to only return PySide/PyQt when they've actually been built and installed with Gaffer.
- Updated my personal build options.
Merge pull request #434 from johnhaddon/pySideBuild

Updated PySide build.