CLC-3528 - Refactor to add course site creation link/button based on Canvas user role

https://jira.ets.berkeley.edu/jira/browse/CLC-3528

* Removes entire previous Javascript functionality and replaces it with logic that checks to make sure that the Canvas user is not registered as a student in any published Canvas course site. If this is the case, it obtains the Course Provisioning application ID via AJAX call to CalCentral, and then inserts link in 'Course' menu.
* When page is loaded for course index page, a button for 'Create a Course Site' is added to top right of main content area.