guzzle version update

[Andrei Sozonov]

Hi!
Can you update the guzzle/guzzle dependency version to dev-master, please?

[Vincent Composieux]

Hi @whyte624,

I've upgraded the master branch (and new 1.1.0 tag) with the new dependency guzzlehttp/guzzle instead of old guzzle/guzzle which is not really maintained.

Thank you!