Merge pull request #1315 from edx/anton/fix-caltulator-a11y

Add a11y to the calculator
Added back on hover CC button functionality.

Fixing falling test. Added fix for RequireJS & XModule loader video race condition.
Removed unnecessary comments from SCSS and JS files.
Added entry to Change Log.
Merge pull request #1344 from edx/valera/add_back_cc_button_mouseover

Added back on hover CC button functionality.
wait to load video module until YT API is ready
Mock YT.ready in Xmodule JS tests

and disable tests that fail for unrelated reasons
Remove references to onYouTubePlayerAPIReady and onHTML5PlayerAPIReady
Rebased. Updated Jasmine describe messages to make them more clearer.
Enabled 2 disabled Jasmine tests. Fixed them.
Remove outdated comment
Enabled 2nd disabled Jasmine test.
Added two states to HD control: HD off - HD on
Updated template and fixtures
Used chaining. Cached gettext call.
Merge pull request #1358 from edx/will/fix-course-overview

Wait for non-blank link in course-overview test
Work in progress.
Updated code fomat in test Jasmine.
Added hard-coded flag to video.html that turns on/off autohiding of captions.

Front-end functionality was not removed. When flag is set to "True", old
behaviour of autohiding of controls and captions will be enabled.
Added functionality to show captions on "CC" button mousemove.

When auto-show/auto-hide is disabled, the captions will be shown when
the user will move the mouse over the "CC" button. They will then
auto-hide after a while if the user doesn't continue to move the
mouse over the "CC" button, or over the captions themselves, or use
the keyboard to select a specific caption. If the mouse pointer is not
over the captions or the "CC" button, they will hide after a while.

This is the key in the fix for bug BLD-355: Transcript hovers over
over videoplayer itself for PKU videos.
Updated fixtures for Jasmine tests.
Added acceptance tests.