Fix -methodSignatureForSelector: for dynamically subclassed classes

Reduce memory usage in rac_willDeallocSignal and KVO subscription

Fix -class in -rac_signalForSelector:, RACCommand KVO crashes

NSUserDefaults and UITableViewHeaderFooterView support, many fixes

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