Improve certificates test time

Speed up test by fixing negative assertion

Speed up test for closed caption state

Refactor heartbeat to delegate to the modulestores and sql

Added manual refund page for support.
PR-615

PR-615

fix reply/return to annotation links

Video: fix seek tracking log.

STUD-1629

bugfix: avoid side-effects when overriding User.default_retrieve_params

Revise course mode choose page.

LMS-2796

LMS-2801

trigger change event for file field while uploading pdf

Fix the CoursePagesTest

implement forums endpoint for searching users.

Add examples of html5 videos to docstrings.

STUD-1775

shim to update ruby/node, not python reqs

Allow xblocks to be added as advanced problem types

FormulaEquationInput: i18n

ChemicalEquationInput: i18n

MatlabInput: i18n

make our HTTP stub services respond to HEAD requests

Fix Jasmine tests for JSInput

Video Test Improvements

Declare variables locally
- The `allSections` variable was leaking into the global scope, due to a
  typo in the declaration.
- `dataProcessed` can be declared more narrowly within the callback.

Clean up fixtures automatically between tests
- Nesting test fixture markup within a DIV allows Jasmine to
  automatically restore the fixture to a clean state between each test
  run.

Fix id attribute collision typo
- This looks like a copy/pasta gone wrong; the two test INPUT elements
  were both declared with the same id, `input_1`.

Remove trailing whitespace