VideoAlphaDescriptor inherits from EmptyDataRawDescriptor.
EmptyDataRawDescriptor is used for modules which might not have any
XML data, but require XmlDescriptor's functionality for
export/import. Without it, VideoAlphaModule would cause a crash on
export if any modules had an empty `self.data` field.

Don't use default video if HTML5 sources are given.

This is to be used with VideoAlpha's functionality allowing a choice
of multiple HTML5 video sources.

tie in the normal courseware link url rewriting in capa module since that presents HTML via an Ajax callbacks and not via module_render.py

Updates comment
Make Model descriptor class property.
Fix tests

STUD-565

Studio: adds in new Sass file for Studio-specific
xmodule presentation and removes full screen control
from video alpha display UI.
Adds jasmine test for subtitles scroll.
Adds tests for caption change height functionality.
Uses gettext wrapper.
Fixes caption change height functionality.
Removes IS_CMS, isCms flags.

Fixes subtitles hiding on slidermove and their height.

Disables tests.
Refactors creation of video element.
Renames renderElements to initialize.
Fixes bug on slider move, subtitles are hidden.

Refactors trigger function.
Fixes Ui bugs: captions.
Fixes bug with Youtube on page load.
Hotfixes html5 video streaming bug.
Adds test video files to the project.

Refactors bind and indexOf.
Adds error message when specify the wrong selector.
Adds some of the requested documentation.
Refactors 01_initialize.js.
Fixes to 03_video_player.js

Fixes HD button
Disables Fullscreen mode in the Studio
Fixes ui controls bug

Video_player_spec wouldn't run because of a syntax error.
All test would fail when error() was called
on an undefined JQuery object.
Tidy up spy on onTouchBaseDevice.
Fix dependecies between RequireJs modules

All the tests run and pass when enabled.
Only video_player has issues left
Adds error logging to console if captions not found
Fix problems with memory leaks

Fixing more tests.
Turned on all Video Alpha tests.
More tests fixing.
Turned on all tests.
Fixing more tests.
Worked on tests at the beginning of video_player_spec.js. Not finished
All Video Alpha tests completed and can be run individually. When run individually - they all pass.
Added jasmine_test_runner.html to gitignore.

Mocked loading of captions.
Fixed remaining tests in captions.
Fixed failing tests in speed control, and quality control. Turned off all VideoAlpha tests because browser crashes when all are run at once. To check that they are passing, go through each file one by one, replacing xdescribe with describe. Dont forget to change back to xdescribe when the test was run and turns out to be OK.
Some tests at the end of video_player_spec.js pass
Further fixing tests in video_player_spec file.
transfers changes to test_logic from master to __init__ and other files
Fixing more tests.

Broken initialize.js. First try at making all submodules functions public (available via state object).
More work on making modules completely visible via state object.
All tests pass in video_volume_control_spec.js
Cleanup of initial CoffeeScript generated video_speed_control_spec.js
Some cleaning up in volume_control. Most tests pass in speed_control
Cleanup of CoffeeScript generated video_progress_slider_spec.js
Most tests in video_progress_slider_spec.js pass (except for those having an issue with subtitles). progressSlider functions again in Chrome
Cleanup of CoffeeScript generated video_control_spec.js
All tests pass in video_control_spec.js
Cleanup of CoffeeScript generated video_caption_spec.js
Some progress in video_caption_spec.js
Fix bug with video progress slider. Now browser doesnt freeze any more. ^_^
Some cleaning up.

Added missing file.~
Undid a mistake.
Copied Python tests from video_alpha1.
moves TestLogic to __init__.py
reorginizes xmodule logic tests
adds docstrings for poll tests
adds docstring for word cloud and conditional tests
adds docstrings for video alpha tests
adds videoalphafactory for tests, not finished
adds imports
Bug fixing.
fix video/videoalpha tests
Updated lettuce test. Now it is aware of the fact that Video and Video Alpha players have different base CSS classes.
Removed REFACTOR comments.
Turn off autoplay for Video Alpha in Studio.
Carry over fix for bug where in Firefox changing to speed 1.0 has no effect.
Carry over JavaScript Jasmine tests from jmclaus/videoalpha2_js branch.
Exporting state object from main function of Video Alpha.
More stuff from jmclaus/videoalpha2_js branch.
Specs in html5_video.js all pass except ten of them. Cleaned code a bit and moved it out of display_spec.js
One more spec passes
Fixed remaning tests in spec/../html5_video.js test suite. Removed test video files.
Added JavaScript Jasmine tests for main of Video Alpha 2.
adds test for volume control and updates helper file for videoalpha

second part of refactoring: JS -> Python HTML
Updated JS code to reflect the change that some HTML generation was moved to python side.
Fixed fullscreen bug - now controls are shown properly below the video. Made the transparency a bit more faded for captions in normal mode.
Fixed bug with captions. Now the attribute show_captions correctly removes them when set to true.
Work in progress.

Making video in the center and not stretched when captions are shown.
Added auto hide/show for captions.
Removed old styling and debug info.
Added missing initalizations for captions auto show/hide.
Fixing bugs. Adding black backgorund to video for when it has not yet loaded. Making sure that the captions are not shown when in YouTube mode.
Added back missing styles for captions when in YouTube mode.
Code review 1 comments
Minor refactoring.
Documenting. Part 1.

Minor fix.
Minor fix. Now state of captions is properly set from cookies.
Fix for hiding-showing subs based on cookie when subs are not found.
Partial feature - hide show controls on mouse.
Removed debugging messages. Changed trigger() method - now it has a better interface.
Better function rewrite. Now .trigger() is more readable and understandable.
In between.

Basic functionality implemented. Core video module can handle HTML5 sources and YoTube video IDs. Play-pause control works.
Added quality change control. Added qtip usage. Removed unnecessary coffee files.
Slight changes.
Added position slider. Enabled several events related to time progress. Work in progress.
Added volume, and speed controls.
Added captions.
Added full support for captions.
Added correct resize functionality to captions.
Petite work in progress.
add autoplay attr for videoalpha tag

Tracing bug in Firefox whereby the HTML5 native video freezes. Turns out that setting currentTime property tiggers a canplay event. And this becomes cyclic because the callback for canplay event updates the currentTime property.
Video alpha 2. Work in progress.

which a previous refactoring had replaced. Coverage of locator.py is
100%