Fix the regsubst flag

When parser = future is enabled in puppet.conf, it doesn't like unqouted flag for regsubst. The new parser will throw out "Error 400 on SERVER: regsubst(): bad flag `g' at /etc/puppet/modules/common/php/manifests/module/ini.pp:25" error. Adding the qoute fixs the problem.
Merge pull request #16 from ubc/fix-regsubst-flag

Fix the regsubst flag