Added support for timeout argment
Cleaner way of getting the 'timeout' argument
Timeout values are no longer globals
Added a custom RoundTrip to have a timeout per request even when the connection is kept alive. More info: https://code.google.com/p/go/issues/detail?id=3362
Simplified RoundTrip by using time.AfterFunc
Merge pull request #13 from Kaidence/add_timeout

Added support for timeout argument