Support for studio-based Video Pipeline.

Allow "colon" in edx-video_ids.
Added get_videos_for_ids method.
Added status and created fields.

@BenjiLee Please review.
This was supposed to be changed in the commit below. 
https://github.com/edx/edx-val/commit/b2285feb9ad00ae32cb3af1f9a02e3e8be3c4da4#diff-2941f25c2b2cbb24bfe43ddd44a814f4