slack notifications / job name changes

As of a few minutes ago, build notifications are being sent to the slack lsstc org in the #dm-jenkins channel. This is in parallel with the existing hipchat notifications, which will be maintained for a overlap period (TBD) with slack notifications.

A few jobs have been renamed as part of some general house keeping work. The changes possibly relevant to general users are:

run-rebuild -> release/run-rebuild
run-publish -> release/run-publish