Determine habit size with ng class

In conjunction with [this habitrpg-shared pr](https://github.com/HabitRPG/habitrpg-shared/pull/397)

Builds upon #3773 

Closes https://github.com/HabitRPG/habitrpg/issues/3260

Takes the logic for applying the habit-wide and habit-narrow classes out of coffeescript, and makes them an ng-class instead.