Don't depend on heavy depencies

Hello all !

This is a huge pull-request which has very little chances to be merged, but it costs nothing to try ;)
I'm working on a PHP lib (Composer: max13/rest-manager) which works on PHP-5.3 and which only depends on php-curl for the requests.

It parses JSON automatically and returns the parsed response (as stdClass) and of course, it's also possible to get internal data (for i.e.: Last called URL, raw response, raw headers, particular headers, ...).
I think your lib would be lighter with rest-manager, here is a pull-request with the coresponding rewrites.

Cheers !