WIP towards Elgg 1.9 version.

This is just to discuss current state and to provide something to test. Do not merge anything.

- [x] Add translations to auto-generated strings
 - ```admin:comment_tracker:upgrade1``` etc.
- [ ] Figure out what to do to the auto subscribe feature  
 - All the stuff using ```COMMENT_TRACKER_UNSUBSCRIBE_RELATIONSHIP```
- [ ] Update CHANGES.txt
- [x] Prevent admin from running subscriptions upgrade before the settings upgrade
- [x] Mark upgrades done
- [ ] Remove unnecessary functions
- [x] Remove debug code
 - ```elgg_dump```
 - ```register_error``` in ```Upgrades_CommentTrackerUpgrade1->run()```
- [x] Remove unneeded code in ```views/default/js/```
- [x] Convert javascript into ADM module
- [ ] Subscribing fails if usersettings include a notification method that's currently not available (the notifications plugin is disabled)