[2.0] Inject PSR18 Client instead of Httplug when using Decoration

[joelwurtz]

So people not using our adapter / interface can still use this library

[dbu]

that would mean changing the typehints on our decorators, right? anything more?

[joelwurtz]

that would mean changing the typehints on our decorators, right? anything more?

That and some instanceof HttpClient present in some parts of the code.

[dbu]

cool, then i am +:100: on this. want to do a pull request?

[joelwurtz]

Will try to do it soon

[dbu]

fixed in #135

(@Nyholm seems that mentioning that in a comment is not enough to trigger github to autoclose the issue ;-) )