Add `show_bunting?` method to Division

This is true if the upcoming event is today and has
the bunting attribute set to "true".
Add `show_bunting?` method to Calendar

This returns true if any of the calendar's divisions
respond to their `show_bunting?` method with true.
Add a wrapper class when bunting is present
Swap in the show_bunting method for the epic-bunting div
Use the ActiveSupport Date helper method today?
Merge remote-tracking branch 'origin/bunting-refactoring'