Update the ios example to use GLKit View and put most logic in controller

Update the GLPaint example to use a GLKit View and put the logic into
a controller. A change to VTK is that it no longer needs the iOSView
as it is using a stick GLKit View.

Change-Id: I83dc90d90b07262cd10e6625a1b053f700c4fe54
Some suggested changes form Casey and remove user files

Change-Id: Ie41a68141ba491552312266eea9ae99459bc1ca1
Merge topic 'update_ios_example' into master

42d91b16 Some suggested changes form Casey and remove user files
8f274310 Update the ios example to use GLKit View and put most logic in controller