dynamically pluralize Notes and Thanks in course and note details

[btbonval]

Pluralize filter: https://docs.djangoproject.com/en/1.5/ref/templates/builtins/?from=olddocs#pluralize

Apply to notes and thanks here: https://github.com/FinalsClub/karmaworld/blob/1cd804f934d6d4b12ca8f43d898fe0f1e4a2b880/karmaworld/templates/courses/course_list_entry.html#L4-L5

Apply to thanks here: (this will require removing the label out of the javascript, which should clean things up nicely to look more like the above case) https://github.com/FinalsClub/karmaworld/blob/bd1f369355a2150bcfbbd79138a483b2a6c40546/karmaworld/templates/notes/note_list_entry.html#L4

[william-bratches]

Added with 141d2449b1f03d0e9a5d31555c1b44210b4bf697; some other changes may be spread out due to my unfortunate barrage of VM commits.