Feature/carter tests

fixed old remove_from_section tests to include resource_link_id
added four new tests to test resource_link_id match, course_id match, conclude_enrollment success and failure
views.py - cleaned unnecessary exception checking from remove_from_section to put it in line with similar functions
removed some unused includes
You could pass 'resource_link_id' : ANY or further simplify it by replacing this chunk  {'resource_link_id' : request.resource_link_id, 'message' : ANY} with ANY as the test case is for checking the status. This is true for most of the test cases, am just commenting  here.