Video Uploading: Implement Video Uploading to the Add Path

As per the spec: http://docs.google.com/a/curriki.org/Doc?docid=0ASxLvDrH5fLEZGd0c3I2cmhfNDFmZnNjaDdmaw&hl=en

Add the ability to Upload a Video to XWiki.

Implement all sections of the Add Path, except for:

1. Progress dialog
2. Changes to the RVE Page.
3. Processing the Video