Update to Guzzle ^6.0

[rdohms]

Replace Guzzle 3.7 with latest releases.

[steffkes]

i'll give this a try and see how it goes - since we're going to use this library in a prototype i feel a bit obligated to tackle one of the existing issues and bring the underlying library up to date ;)

[steffkes]

we're postponing our project, which means i'm currently no longer trying to port the library over to the latest guzzle release.

in the beginning it looked somewhat easy, but the whole test infrastructure is gone for guzzle5/6. i mean, there are still mocks and stuff for tests, but the way that guzzle likes to be tested in the latest releases is way different than it was back then.

so that will require a bit more effort. will see if i can resume that task when we're working again on our project.

[jasonkhanlar]

Hello. I am interested to contribute, but instead to work on porting to be compatible with Guzzle 6.0. I am available on Freenode IRC network #guzzlephp to discuss as clevodearia/sagerdearia

[rdohms]

Updating this to actually move straight to Guzzle 6.0.
Currently this is not possible since we rely on guzzle-services which have not yet been updated.

There has been discussion and its being done in guzzle/guzzle-services#89 so we will keep track of that and update our end once that is done.

[azine]

+1