Github api instead of raw guzzler

I'm submitting this PR before it is complete.  

I'd like to solve https://github.com/Bee-Lab/bowerphp/issues/49

I think the solution is to wrap the app in a try catch block and look for ```Github\Exception\ApiLimitExceedException``` then prompt the user to login then prompt them to re-run the command.  

There's a lot to change to make this work.  This will be one hairy PR when it's done.  

Feedback is appreciated.
Can you leave changes on this file out of this PR? It looks unrelated.