Track commit review better

[geofft]

We should have some better mechanism for tracking commit review, specifically some mechanism for noticing outstanding unreviewed commits.

Currently we have commit review by replies to the commit mail on source-commits, but past that, we track the status of commits, if anywhere, on Trac. Nice things to do would include setting up the Trac post-commit hook, deciding that every commit should have a corresponding Trac ticket of some sort, having a little script subscribed to source-commits that lists commits that haven't been ACK'd yet, setting up Rietveld, etc.

[jdreed]

I think we sort of have this now with Github?