[Issue #1296] Adding AFURLSessionManagerTaskDelegate
Removing unused allowsInvalidSSLCertificate property from AFURLConnectionOperation
Make  return  and no error if .

Signed-off-by: Mattt Thompson <m@mattt.me>
Updating podspec
Renaming AFServerSentEventSerializer -> AFServerSentEventResponseSerializer
Bumping minimum platform requirements to account for change in dispatch storage
Replacing upload/download progress block with NSProgress object
Fixing implementation of NSProgress in AFURLSessionManager
Assigning framework dependencies based on subspec requirement
#pragma formatting
Adding AFURLSessionManager -uploadTaskWithStreamedRequest:progress:completionHandler:
Implementing -URLSession:dataTask:didReceiveData: