change the way AFNetworking pair the key in case of NSArray. (for exam: in original AFNetworking code array key when encoded as x-www-form-urlencoded : arrayname[]=value1&arrayname[]=value2 ...
in modified version for imagnet, we use: arrayname=value1&arrayname=value2
Merge branch 'master' of https://github.com/phamquy/AFNetworking

# By Jackode
# Via Jackode
* 'master' of https://github.com/phamquy/AFNetworking:
  implement login method