Add video upload feature to Studio

This still needs to be audited for accessibility.

Please review: @nasthagiri @andy-armstrong @frrrances @talbs 
FYI: @clrux @doctoryes @karadhya 

*JIRA Tickets:*
* https://openedx.atlassian.net/browse/MA-28
* https://openedx.atlassian.net/browse/MA-85
* https://openedx.atlassian.net/browse/MA-86

*UX Design:* https://edx-wiki.atlassian.net/wiki/display/UX/Video+Uploads+in+Studio
*Functional Spec:* https://openedx.atlassian.net/wiki/display/MA/Video+Pipeline
*Sandbox:* http://studio.video-pipeline.m.sandbox.edx.org/

The recent RequireJS Optimizer hackathon project (https://github.com/edx/edx-platform/pull/6036) made use of the RequireJS text library to declare templates as dependencies. This has several benefits:
 - Mako templates no longer need to statically include every needed template in the HTML
 - the template lookup is much faster when optimized as it doesn't have to extract it from the DOM. For developers, the template is fetched asynchronously like any other RequireJS dependency.
 - the templates get included in the minified .js file for the page so the content is only downloaded once and then cached in the browser. Including the template in the Mako template causes it to be downloaded every time.
 - unit tests don't need to load all the templates into fixtures for the views to work, as the view will load its dependency directly

We would very much like all pages going forward to be built this way. If you'd be willing to do this it would save us from having to convert this later. Let me know if you want more information as to how to do this. I'm also going to add these details to my wiki page.