Add course and term names under group listings

Multiple groups with the same name are now better identified with their
context names (and term names if they are courses).

Test Plan:
  * Create two courses, with one of them in the Default Term
  * Create course groups in those courses
  * Add a student to both course groups
  * As the student, go to /courses
  * Make sure the course name appears under the group name
  * Make sure the term name appears (unless it's in the Default Term)
  * Do the same for /groups
Fix group name tooltip in courses#index

Test Plan:
  * Create a course group with multiple words
  * Add a student to that group
  * As the student, go to /courses
  * Hover over the group name
  * Make sure that all the words show up in the tooltip
Use term styling for groups in courses#index

Test Plan:
  * Go to the courses page (/courses)
  * Look under My Groups
  * Course name/term for groups should be displayed like terms
    for courses
  * Course term (if any) should be in parentheses
Merge pull request #509 from sfu/fix-group-context-take2

Add course and term names under group listings

Change-Id: Ibb90c7a511771a27f55c5f77649191d4ef1a41c9