created a class list view

This allows instructors to view the people in their class.
The users/edit feature can also be accessed from here.
Created a users view page

Users can access this page from the course classlist
made various implementations throughout the app

- added create user permissions for instructors
- added hybrid property to PostsForQuestions and PostsForAnswers to
calculate the number of comments in each question, answer, and the
total
    - modified "number of comments" placeholder to actually show
      the total by using the new hybrid properties
- changed the url to teh calss list from #/course/:courseId/classlist
to #/course/:courseId/user
- hid the "Create Question: button from students
- added links to comment authors' profiles (just like the links for
authors of questions and answers)
- modified user's profile
    - can only see private information such as full name, user type,
      and email if the currently logged in user can create user (ie.
      students can view private information)
    - added new informatin: last online, user's creation date
- added tests for classlist api