Auto Registration Feature

When starting the minion-agent for the first time, we should be able to automatically register its presence in the customer's cluster. To do that the configuration file of course needs the user's group ID and key, but it also has to have a UUID present in the configuration file.

So that's a problem if you have a custom AMI, for example, with the configuration file already "baked" in there - a new machine based on that AMI would take the place of whatever machine previously had that UUID.

A better approach would be to have a config file with the UUID blank, and then _have the agent populate that UUID_ when it first communicates with the API on first launch, then the API can give it its UUID (useful in the unusual circumstance that `uuidgen` isn't installed) and the agent can save it in the config file. So, in other words:

1. Agent start
1. Read config
1. Do I have an ID (UUID) already?
1. Yes? Continue
1. No? "Register" with the minion API
1. Get your unique ID
1. Save the unique ID in the config file
1. Agent restarts itself going back to 1.

This is going to need an API end point and some logic in the agent itself.