Do not consider EC2 instances in terminated state.

The terminated instances aren't coming back :)

We didn't add this new condition to the `unless` statement for two reasons:

 1. Our version of `zonify` has a lot more going on in there besides `unless` :smirk_cat: 
 2. It's hard to reason about `unless` statements that have lengthy boolean expressions in them without a couple of shots of scotch or whatnot.