Set up monit to monitor app services

The monit dashboard is available at port 2812, or 2067 on Vagrant. It
currently only attempts to restart failed services; it doesn't send
alerts based on CPU usage, disk space, etc because it wasn't clear how
that would work for transit agencies.
Don't install Monit on Travis

It's not necessary and could potentially lead to strange build failures
if Monit relaunches services not intended to be launched on Travis.
Merge pull request #155 from WorldBank-Transport/feature/monit

Set up monit to monitor app services