Better fix for trailing slash

New URLs require a trailing slash

Bug/tomg/collapsible hint

Feature/ibrahim/followed threads

Remove commented out block and pull some stuff into a function to load the first page of results for a thread query.

Conflicts:
	lms/djangoapps/django_comment_client/forum/views.py

Match custom static tabs after discussion URLs so that discussion can actually work.

Feature/victor/static tabs

adding pkg-config

fix ubuntu graphviz lib install

Properly puluralize comments tooltip and change "unread" to "new".

Show total comments instead of unread only, and use a tooltip to show th...

darker background for read posts

Unread counts + tracking for discussion

Change unread to read; makes some things clearer both on the comment service and in the django client

Change unread to read; makes some things clearer both on the comment service and in the django client

- move courseware wiki views above catch-all rule
- handle courses with no custom tabs

* still needs better error checking and testing

Update doc/xml-format.md

Prepare lms for upcoming discussion service changes.