Proposal: use only github for new MSE spec bugs

At the moment, we are using both w3c and github to track open MSE spec bugs.
At the recent FOMS 2015 & Demuxed 2015 conferences, we heard praise from
other attendees of the move by EME to primarily using github's issue
tracker.
In light of EME's move to gh for new issue tracking, external appeals of
similar for MSE, and to consolidate tracking of all new MSE spec bugs, I
propose that we move to using solely github for tracking newly opened MSE
spec bugs.

Before moving forward, I would like to understand better:
1. Would it make sense to make placeholder github issues for existing,
open, w3c MSE bugs, and restrict all MSE spec bug activity to github issues?
2. Is it possible to update the w3c bug tracker to indicate that new MSE
bugs or activity on existing w3c MSE spec bugs should occur on github's
issue tracker?
3. Which versions of the MSE spec would need updating to reference using
github as the primary issue tracker for spec bugs (just the current
editor's draft, or some retro-active editing of earlier published snapshots
of the spec too?)

Thanks,
Matt