Add ENABLE_WHITEBOARD setting.
Fix PEP8 warnings & some typos in basic view.
Add whiteboard_enabled to weblate_context.
Fix PEP8 warnings in context_processors.
Add dummy Whiteboard section on index page.
Add WhiteboardMessage model.
Add migration for WhiteboardMessage model.
Adjust Whiteboard model so it's discoverable by Django.
Output whiteboard messages on index page.
Fix typo in spec file.
Fix style issues in unit model.
Fix style issues in appsettings.py.
Style fixes for admin.py
Add whiteboard message to admin UI.
Add test for WhiteboardMessage view.
Add tests for whiteboard section on home page.
Fix typo in AdvertisementAdmin.
Style adjustments in admin_views.
Move initialisation of created variable to top of UnitManager.update_from_unit().
Fix typo in po files as well

Signed-off-by: Michal Čihař <michal@cihar.com>