Pass group_id when getting user thread and comment counts.

TNL-543

Related cs_comments PR is https://github.com/edx/cs_comments_service/pull/122

@jimabramson @dan-f Please review.

Can use my sandbox to test--
http://cahrens.m.sandbox.edx.org/courses/christina/foo/bar/discussion/forum

This course has the following users and posts:
1) staff@example.com has moderator access. staff has started 3 discussions-- one to general (not cohorted), one to Verified Group, one to Honor Group. staff has also commented on two posts-- one written by honor to everyone, and one written by honor just to Honor Group cohort.

2) honor@example.com is in Honor Group. honor has created 2 posts, 1 to everyone and 1 to Honor Group. honor has also commented on both of those posts.

3) verified@example is in Verified Group. verified has created 2 posts, 1 to everyone and 1 to Verified Group.
ohh...i guess in the test cases the user id in the requests is (sometimes) the same because they have the student looking up the profile for themselves...right?  while in practice when user X requests the user profile view for user Y we should see one request for X (no course_id) and one for Y (with course_id, and with group_id as applicable).

i guess i'm cool with how this is working now - one thing that worried me is that as currently written, under some circumstances you could have false negatives (if course_id were omitted from the request where presently expected, is the main one i can think of).   a smallish change that would fix that would be to make user_info_calls a dict instead of a list, with the keys being their associated course_id, and then you can make assertions by directly referencing them instead of in a loop.