Feature/sm list of users

Unit test  cases  for section_details method  This method displays list of enrollments on a section id being passed in. 
Most of the test cases were developed by  all 3 of us (Carter, Josie, Sapna) in a developer working session.
I have an incorrect comment for this method.  The section id is always passed in as a numeric String  via the request. There is a step in the section_details that converts it to an int (as the backend method expects an int). And as we have mocked the  backend 'get_section_enrollments' method,  this use case would pass  and display the section_details.html as reflected in line 753.  The comment is misleading, I will correct it.