Video embed sanitizer

RELEASE NOTES: The syntax used in the embed code for most video hosting sites (like Youtube) has changed. Our sanitizer wasn't recognizing the new version and was therefore stripping out most video embeds. This should now be fixed. We are also now allowing video embeds from youtube-nocookie. 

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Fixed embeds sanitizing to allow different syntax for src (with no protocol), fixed test and made more robust
Also added youtube-nocookie to allowed sites

https://code.google.com/p/otwarchive/issues/detail?id=3814
https://code.google.com/p/otwarchive/issues/detail?id=2992