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
Looks like this block was cleaned up and it looks much cleaner and simpler now without multiple try-catch blocks for almost  the same error handling. Along with user_section_id,  I would suggest logging  the canvas_course_instance_id, to make it more useful to track which course this error occured in