Clear cache on the uninstallation of a mod 

I have found this to be an issue within automod itself in that it doesn't clear the cache on the uninstallation of a mod, hence why the removal of some mods will break a board.

Currently on uninstallation, the original files are restored, however the modified files remain in the cache unless the admin does a manual cache refresh or runs some other uninstall script (database edits) which then refreshes the cache.

Very simple fix to address an issue affecting mod removal as well as a requirement to satisfy mod validation (install / use / uninstall)