HTML5 videojs.com video player implemented as suggested in issue #8
Merge github.com:jamalex/ka-lite into develop-html5

Conflicts:
	kalite/templates/base.html
	kalite/templates/video.html
Merge github.com:jamalex/ka-lite into develop-html5
Tweaks to VideoJS integration.
Security fix for django-wsgiserver to prevent escaping from media path.
Replaced django-wsgiserver with cherrypy itself, to fix streaming issues.

Wrote a custom wrapper that serves everything through the cherrypy static
file handler, which supports byte range requests, and thus scrubbing.
Added host overriding in cherrypy server options.
Merge branch 'develop' into videojs

Conflicts:
	kalite/templates/video.html
Better constrain video player to the screen dimensions (max height).
Rename internal video.js to videoplayer.js to avoid confusion.
Changed script to only produce po file for demo purposes.
Merge branch 'develop' of github.com:jamalex/ka-lite into develop
Updated video page to auto-resize video player constrained to viewing area.
Wrapped javascript for exercises for i18n.
Removed khan exercises from gitmodules.
Temporarily renamed khan exercises.
Included khan exercises directly in the repo.
Fixed alignment bug for coach reports (again).
Rearchitected the VideoJS player with a Backbone wrapper w/ point counting.
Moved khan-exercises to avoid conflicts with old submodule.