Cope with different implementations of flymake-phpcs.

There now exists two different implementations of a flymake-phpcs.el:

 * [senda-akiha/flymake-phpcs](https://github.com/senda-akiha/flymake-phpcs)
 * [llusori/emacs-flymake-phpcs](https://github.com/llusori/emacs-flymake-phpcs)

Drupal-mode has supported @illusori's version for quite some time and unfortunately @senda-akiha's version needs to be invoked in a different way and variables are named differently.

The problem gets worse because @illusori's version has been in [Marmalade](http://marmalade-repo.org/packages/flymake-phpcs) for a long time and now @senda-akiha's version has been added to [MELPA](http://melpa.milkbox.net/#/flymake-phpcs). Users will now risk being "upgraded" to @senda-akiha's version without noticing - and things will break.

I'll try to support both versions.