Added RACCommand support to UIButton.
Changed debugger back to LLVM.
Fixed UIButton RACCommand support unit test.
Addressed code review issues from pull request.
Marked UIButton+RACCommandSupport.h as a public header.
Cleaned up UIButton+RACCommandSupport.m
Merge remote-tracking branch 'github/2.0-development' into uibutton-command

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa.xcodeproj/project.pbxproj
Merge pull request #558 from AshFurrow/uibutton-command

Added RACCommand support to UIButton.