Adds NG states to php-formula

This rather big pull requests adds NG states to the php formula much in the same way we did with NGINX. It does require the helium release (or an updated pillar module) in order to take advantage of `salt.modules.pillar.get(merge=True)`.
I love cheating like this. We only have to write the installation state once and the `{{ state }}` variable does the rest of the work for us. It's not dissimilar from doing it with a macro (also used) but arguably simpler.