CYB-377 Youtube URLs are not always https

* changed the regular expression where it matched the protocol to always match
    http:// or https://
* This will ensure that Youtube videos are handled as such.

[CYB-377 Youtube URLs are not always https](https://jira.ets.berkeley.edu/jira/browse/CYB-377)
My understanding is that the regexs were written that way so that any valid form of a YouTube URL would be supported. My read of the above (and my regex-fu is poor) is that it would not cover all the permutations. 

We should test that with YouTube we can support:
- https://www.youtube.com/watch?v=_wYtG7aQTHA
- http://youtu.be/_wYtG7aQTHA
- www.youtube.com/embed/_wYtG7aQTHA
- http://www.youtube.com/attribution_link?a=vWWTV--xCE8&u=/watch%3Fv%3DeOS20plm7UM%26feature%3Dem-share_video_user

>>> OK, maybe not that last one… that's what you get when you email a YouTube video to another person