First draft of configuration proposal.

@smarterclayton 
Starting point for discussion. Feedback welcome. Also let me know where you'd like more detail.
Would that be best modeled as two separate configs?

```
config 0: two replcontrollers, one service
config 1: three replcontrollers, one service (not pointing to new repo)
config 2: two replcontrollers, one service (pointing to new repo)
```

I'm not sure that simplifies things, but it does at least put the onus on the config creation process to handle that.