BAC-1241: RL caching policy updated

* cache "static" modules for 30 days (when cb in URL matches $wgStyleVersion)
* cache "dynamic" modules for 30 days (when version param is present and matches module's $mtime)
* force 30 days caching for "startup" module
Update unit tests
Feedback from @wladekb
Merge pull request #2880 from Wikia/bac-1241-rl-caching

BAC-1241: RL caching policy updated