Introduce RAC
Refactor api method calls to return RACSignals
Remove CKPagedResponse from umbrella header
Stop ending signal before sending any data.
Merge remote-tracking branch 'jasonl/RACAttack'

Conflicts:
	CanvasKit/Networking/CKIClient+CKICourse.m
	CanvasKit/Networking/CKIClient+CKIFavorite.h
	CanvasKit/Networking/CKIClient+CKIFavorite.m