Fix how service actions are invoked.

Fixes issue #194.

This pull request is some initial thoughts on how to prevent docker service definitions from squashing over each others actions.  Here, the service should (most likely) only be defined once and from there have it's action invoked immediately.  Using this immediately fixed issues I had with redeploy.

Another possible solutions could be using `docker rm` instead of  `service_action(:stop)` in `def stop`.

This may or may not be the best way to solve this problem but I at least wanted to throw this up to get some feedback.