Added the ability to deploy CoreOS instances on AWS

New commands possible are...
```
skipper instances deploy
```
Deploys instances listed in skipper.yml
```
skipper instances ps
```
* Lists all running instances.
```
skipper instances remove [uuid]
```
* Removes a running instance.

```
skipper instances ssh [uuid]
```
* SSH into a running instance.
Merge pull request #21 from cameronmaske/core-os

Basic CoreOS instance control