Added a script to compare current parser output to cache

* This works on a random set of pages in a namespace and can
  be used to compare different PHP interpreters.
* This can, like any maintenance script, be used with --profiler.

Change-Id: Ica69a3ef27df29af1c6e4dc4c8413b55a03df49e
Merge "Added a script to compare current parser output to cache"