New API using AFNetworking 2

This commit introduce a complete revamped architecture and API design and is rewritten updating to AFNetworking 2 and using the new iOS 7.0 only API (NSURLSession)

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Update podspec

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>