YouTube URL validation

[brasky]

need to prevent incorrect urls from being submitted.

[brasky]

When copying a url from the youtube mobile app the url is not supported.

example: https://youtu.be/nrkgEXh5CSU

edit: this must have been a fluke... working now...

[brasky]

Added basic frontend validation a603c38

Need to add a server side check in SyncHub.NewVideo before sending the ID out to all the clients.