Initial work on LTI module.

Created a blank python module for LTI that contains 2 fields. A JS stub was
also added.
updates
updates
Rewrite of LTI template. Moved all JavaScript to JS file.
update
updates
updates
Tweaking of LTI.js

Added error message for the case when the action URL is not provided.
Fixed error when it was not loading in LMS. Now the element passed to
the LTI constructor function is handled correctly.
Added comments.