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.
Updated video page to auto-resize video player constrained to viewing area.
Rearchitected the VideoJS player with a Backbone wrapper w/ point counting.
Merge branch 'develop' into videojs

Conflicts:
	kalite/templates/exercise.html
	kalite/templates/knowledgemap.html
Pass video dimensions in to Backbone view to ensure auto-resizing.
Added speed changing button on HTML5 player.
Re-added exercise files to khan-exercises.
Bumped version number.
minor tweak to avoid errormessage on osx