show treeherder status summary

[tromey]

It would be quite nice if bugs in the "to check in" panel also showed a brief summary of the status of any try push for the bug. In particular it would be nice to see (1) if a try push has been done, (2) the %-completion of the run, and (3) have the summary be a link to the appropriate treeherder URL.

Currently I have a separate treeherder window open, but since I can't easily drop "uninteresting" builds from it, it's a bit of a pain; also it would be great to have one dashboard rather than two.