Replace CURL by Guzzle 5

[younes0]

Should improve speed, you can also easily mock requests, these are few of the benefits.
I may do this one, what do you think?

[oscarotero]

I don't think guzzle should replace curl but added as another choice should be great.

Feel free to create a new PR with a Embed\RequestResolvers\Guzzle adapter.

[younes0]

Okay great, will do