use "escaped" instance name for ssh target
use "escaped" instance name for ssh target

so here's the deal:

* systemd escapes '/' to '-' in instance names, presumably for the sake
  of having filenames in there
* ssh targets often have '-' in them (i.e. cf-app.com)
* using `%I` (unescaped form of `%i`, instance name) seemed like a good
  idea at the time, but apparently systemd just applies the inverse
  filter on it, making the '-'s turn into '/'

given that ssh targets should never have '/' in them, this is what we
want, even though it's kinda misleading

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse