Reimplement AFMultipartBodyStream as AFMultipartBodyStreamProvider vending one side of a bound CFStream pair, to avoid subclassing NSInputStream and fix #781
Delete useless commented-out call to handleOutputStreamSpaceAvailable, and fix the stream:handleEvent: bit flag check
Fix deadlock from trying to do a dispatch_sync on the main queue when already on the main thread
Merge branch '781-mime-stream-pair' of git://github.com/plausiblelabs/AFNetworking
Minor refactoring / reformatting after merge
Re-implementing throttling in stream provider architecture