mediawiki: small clean-ups

* Instead of a fake sync to start Apache on beta (bug 38996), call
  "/etc/init.d/apache2 start".
* To avoid having the beta Apaches attempt to sync the Apache configs,
  create File['/usr/local/apache/conf'] before sync_apache_config has had
  a chance to run.
* Tidy up whitespace, parameter order, etc.
* Avoid redundant dependencies when Puppet already orders resources.
* declare apache::mod::cgi

Change-Id: I1b8a617c260bb68ec475656aa56a500a6ab0ad5d
Merge "mediawiki: small clean-ups" into production