Added link to creative commons bug 842822
Add zh-TW and ja to PROD_LANGUAGES.
Remove zh-TW from PROD_LANGUAGES.
Merge remote-tracking branch 'bensternthal/rules-cc-link'
Gallery page updates, et. al.

* Revised layout, moved trailers to sidebar
* Added promo trailers
* Moved locale-sensitive links to settings/locale.py
* Moved main submit button to far right position
* Fix bug 841494 - alt attributes for image links
Use urlparams for submit hash
Update home JS to make both submit buttons work.
Bug 840716: Download thumbnail image instead of storing URLs.

- Adds an admin command to download thumbnails for existing videos.
- Alters the approval processing to happen synchronously on save instead
  of asynchronously via celery to help lower the risk of making a video
  public before it is fully processed.