Proposal: Move PHP sample configuration from the default site config into a snippets/ file and then include the snippet

One thing that I"ve always wanted to do is simplify the ability for people to enable services without needing to handwrite entire blocks for each site. This is what snippets/ has been for - to load snippets repeatedly into code without needing to duplicate the entries (except for include tasks.

I'd like to propose that we move the PHP configuration snippets from our sites-available/default into snippets/php.conf - this way it's much easier for someone to include the PHP code in their own site configs. Additionally, we will replace the entry in default with a "If you intend to use PHP, please uncomment this line to use a set of default arguments that should work. Review the snippets/php.conf file if you want to see exactly what is set." stanza.

Thoughts before I put the effort into making a patchset for this here in git?