fix for install/startup bugs caused by package getting installed before ...

Installing the package before config files meant that a restart was required when the templates were written and they changed.

But if you changed the nodename this restart was broken.  Rabbitmqctl would try to find a server on the new nodename to stop and not find one, then try to start the new one which would fail because the daemon was already running.

Writing configs before installing the package fixes this.