Post uikit-dynamics-catalog Custom Dynamic Item for code review

Hi Will,

This is not a request to merge but just a code review request (if you have the time) before I submit a RubyMotion bug report. If you are tight for time just say so - I'm fairly convinced that this is a RM bug but thought I'd get your thoughts before I submit.

If you do have the time could you please review CustomDynamicItemViewController especially def button_action(sender) and animator.addBehavior(attachment_behavior)

The animator, with the above addBehaviour method invokes the protocol method def bounds contained in PositionToBoundsMapping class

rake crashlog is showing something going sour at the point at which the protocol method bounds is accessed.

If you don't see any obvious screwup in my conversion of the code then I'll submit the bug report.

Thanks.