MOB-2272

* changed maintenance script `wikia/messaging2files.php` to have a tool to upload messages from `messaging.wikia.com` to a file(s),
* imported messages from messaging to `i18n` files,
* added new translations for parent POI categories (translations taken form Jira ticket),
* added logic in model to use translations instead of hardcoded DB data for parent categories.
Nitpicky ;), but "overwritten" isn't quite what happens, it appends to the file and only if there are [no current translations for a given language](https://github.com/Wikia/app/blob/9d5cf7e2b10d/maintenance/wikia/messaging2files.php#L76). It would probably be good to have an option to overwrite all the non-English and QQQ translations so it pulls completely fresh translations from messaging (making sure to save any translations that are in the file but not on messaging), but that's more of a nice to have and can be pretty much achieved with the -v option anyway.