Buncha bug fixes

Fixes in xcconfigs, RACCommand.enabled, -rac_signalForSelector:

Fix RACObserve with NSController, -rac_signalForSelector: fixes

Fix analyzer warning, UIRefreshControl support, optimize -any:

Fix -bind: termination, -connect race, add -try: and -tryMap:

Fix RACSerialDisposable memory leak and race condition

Optimized +empty, +return:, and +error: signals

New categories, optimized compound disposables and subscription

Move RACExtensions into framework, add Instruments template

ReactiveCocoa 2.0 Golden Master