Change channel subscription to happen in groups (#1166)
Change channel subscription to happen in groups (#1166)

This means that the application won’t block while subscribing to the Pusher
channels. Some events could be missed as the channel backlog is subscribed
to, but it will make the site usable for people who have permissions on
large numbers of repositories.
travis-ci/travis-web,travis-ci/travis-web,travis-ci/travis-web,travis-ci/travis-web