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 approach we use now for RequireJS optimizer is to move all of the page view construction logic into a single factory file. This is so that the optimizer can statically determine all of the dependencies the page requires when it produces a single minified file.

Look at container.html for example:

https://github.com/edx/edx-platform/blob/master/cms/templates/container.html#L37

You should then list your new factory in this file:

https://github.com/edx/edx-platform/blob/master/cms/static/build.js#L24

I think this is all that you need to do so that your new page benefits from RequireJS Optimizer. I've added this information to my new wiki page describing how to add pages to Studio:

https://openedx.atlassian.net/wiki/display/TNL/How+to+add+a+new+page+to+Studio