Adding front-end functionality for multiple new window open of LTI.

Updating from with new signature.
Add tests and fix.
Fixing failing python test.
Add getting client and  secret tests.
Modernized LTI JavaScript code.
A proper constructor. All functions are now in the LTI object's prototype.
The idea is to make it easily testable.
Adding comments to JS code for LTI.
Adding further comments to LTI JavaScript module.
Add signing body tests.
Refactor.
Simplify test.
Add tests.
Adding Jasmine tests.
Fixing Python LTI tests.
Fixed and simplified tests.
Fix tests and generate right url scheme.
Fix tests.
Rewriting and updating LTI JS and tests.
Simplify test.
Rewriting LTI JS part using RequireJS.
Fixing invocation of signature AJAX update callback.
Fixing Jasmine test.
Jasmine test for form update with new OAuth values.
Add Jasmine test for when inccorect AJAX response with OAuth signature is received.
Updated Change Log.
Addressing Alex's comments.
Fix python test.

BLD-465.
Removing work for BLD-465.

Separate PR handles BLD-465. PR 1856.
Fixing Python test fail.