Parameterize classes

I did some work to better parameterize the classes so that the class parameters can be more easily overridden using Hiera. Are you open to something like this? I'd prefer not to maintain my own fork.

I don't have a Debian box handy, so I left a couple of the parameter defaults as 'TODO' -- that'll need to be corrected.

I made a couple other changes while I was at it, so if you would prefer me to split those out into separate PRs, I'm happy to do so.  Specifically:

- Added an option to manage the httpd php.conf file or not -- default in params.pp is true so that the default behavior doesn't change.

- Added an option to not automatically restart apache for php.ini changes. Again, this defaults to true (will restart apache), so that the default behavior doesn't change.