References for HbbTV contribution to the W3C Inband Tracks Community Group

These are for amendments that will ultimately end up in https://github.com/w3c/HTMLSourcingInbandTracks. I hope that the new ones are non-controversial.

I am proposing to update the MPEGDASH reference to the 2014 version; it used to point to the 2012 version. To my knowledge that should be fully backwards compatible, so hope this one to be non-controversial, too.