update afnet dependency to latest 2.x series
added NSURLSessionConfiguration support
remove hook to cater for iOS 5 bug
refactor AGHTTPClient to use AFNet 2.x API
refactor AGRestPipe to use AFNet 2.x API
refactor AGRestAuth/Authz modules to use AFNet 2.x API
update podspec to use afnet 2.x
cater for previous failure count per challenge
be cautious on what you 'Accept:'
timeout can be passed as a param
update api doc for progress block
fix compliler warning, length type in-sync on what afnet expects in 2.x
added 'cancel' tests
use constant NSURLErrorTimedOut
use latest afnet 2.2.1 release
update xcode proj. settings after rebase