Sort using using lexicographical byte value ordering

See 9.1.1 in http://oauth.net/core/1.0/
> Parameters are sorted by name, using lexicographical byte value ordering.

This is already fixed in Guzzle4, but a patch to Guzzle3 would be appreciated, as I encountered this bug, in my case when posting an array with more then 9 items.
Also see https://github.com/guzzle/guzzle/issues/558 and #4