Demo arbitrary starting angle for PieView

This pull request corresponds to somethingkindawierd's pull request adding an arbitrary start angle to the PieView.

My changes here add 3 new pie views to the demo, showing the effects of the arbitrary angleOffset and custom max progress values.

I adjusted my fork so the sstoolkit submodule points to my fork of that project, so if you accept the changes you should only need to merge the `Classes/SCPieProgressViewDemoViewController.m` file.