Improve error messages from rabbitmqctl when the rabbit app is stopped
Exit early if rabbit app is not running on target node (but not for all commands)

Some commands can be (or should be) used when the rabbit app is stopped,
e.g. stop_app or reset.
Refactor
It's easier to specify the commands that do not require the app than those that do. Also reduce name verbosity and remove a stray call from action/eval.
Use a list of commands that do not require rabbit app to be running
Use rabbit:is_running/1 here
merge heads
Use rabbit:is_running/1
Reduce distance to default.
Cosmetic.
Don't report nodedown issues as rabbit app not running
Refactor: move ensure_app_running inside the big catch block, then we don't need to duplicate error handling.
Nicer formatting of error message.
Merge bug26242