More frontend integration with admin options for content creators.

Superusers will see the lessons screen along with lessons that still need content appended to them. It then links them to the content creation screen with the corresponding topic filled out.
Shifted admin-related UI components to template responsibility.
Some basic notification/error handling.
Lots of localization updates (esp. to support Farsi):

- New UI components CSS marked up for flipping.
- Fixed visual bugs related to RTL display.
- Marked strings for translation in both js and template files.
- Lesson tasks now pull data from set language of user.
- Changes to database, to demonstrate how content should be added to grammar topics in the UI.
- Ran commands to collect localization files for FA, DE, IT, HR.
Merge pull request #49 from OpenPhilology/development

Admin and Localization features.