Merge branch 2.0 into master
Quick update to README
Ensuring that start and stop animating for UIActivityIndicatorView category are called on main
Ensuring that progress is set in UIProgressView category only on main
[Issue #1336] Updating response serializer validation error message to be more appropriate in user-facing situations
Adding documentation for AFSecurityPolicy
Updating documentation for default session manager response serializers
Adding upload/download progress animated associated objects

Using af_ prefix on associated object properties
Adding __unused declarations to fix warnings
dispatch_sync -> dispatch_async
Enabling and fixing extensive compiler warnings
[Issue #1366] Adding shouldUseCredentialStorage and credential properties to AFHTTPRequestOperationManager
Adding documentation to AFNetworkReachabilityManager
Minor edit to AFHTTPSessionManager documentation
Adding first pass of example usage
Cleaning up AFNetworkReachabilityManager
Replacing use of hard-coded keypaths with equivalent NSStringFromSelector of selector literals
Replacing use of hard-coded keypaths with equivalent NSStringFromSelector of selector literals in AFURLSessionManager
Adding note about Apple's Reachability sample code
Changing contact information