Fix bug multiple choice with video. BLD-788.

The Video element contains an input with type file. When the
Check button was clicked for the multiple choice problem, the
code was acting in different ways when there as a Video on the
page and when there wasn't. This is because in the check_fd()
method there was a selector that was looking for inputs of type
file on the whole page instead of just in the current problem.
When there was a Video pn the page, the page-wide selector
returned the Video's file input, and the check_fd() method
went on believing that the multiple choice has a file input.

The correct way is to look for file inputs only in the current
element.

Added a Jasmine JavaScript unit test.

BLD-788.
Merge pull request #2618 from edx/valera/fix_multiple_choice_video

Fix bug multiple choice with video. BLD-788.
Use new setting for LMS deadline display instead TIME_ZONE
Merge pull request #2676 from edx/jbau/timezone-hotfix

Use new setting for LMS deadline display instead TIME_ZONE
Merge pull request #2602 from cpennington/xblock-acid-child-tests

Add tests of the frontend children api using the AcidXBlock
Merge branch 'release'

Conflicts:
	lms/templates/courseware/accordion.html
Make staff view work w/ pure xblocks (that only have a descriptor system)
Add test of local_resource_url in AcidBlock
Add tests of more scopes in student_view