Use guzzle instead of jsonRPCClient

[vv12131415]

I was looking at the code and noticed that it will be cool to use guzzle instead of/ inside of jsonRPCClient
since guzzle does all the dirty work that you need to do your self (doing all the stuff with curl_setopt)

[serhack]

We'll consider that in the next version! Thanks for the suggestion

[vv12131415]

We'll consider that in the next version! Thanks for the suggestion

then let's do versions, because on packagist it's dev-master currently