Fix PHP getter and setter UltiSnips snippet

Was broken due to complex regular expressions applied to $1,
which made UltiSnips to complain about not knowing it.

Simplified the snippet using the already working getter and setter snippets.
Merge pull request #321 from adoboPullRequests/master

PHP, Ultisnips: Fix getter and setter snippets that contained an invalid reference.
Merge remote-tracking branch 'upstream/master'