Add ability to deploy, remove and see the status of launched services.
The following new commands are available...

`skipper deploy web:v1`
    - Launches a service across the desired instances.

`skipper remove web_1`
    - Removes a running service.

`skipper ps`
    - Displays the status of running services.

Other changes include...

    * Added Group classes to aws host. Groups house all the information needed to launch instances.
    * Rework aws host to get creds, private keys only when needed and thus only prompted the user for them when needed.
    * Aws host's `all_instances` now looks across all regions.
    * Updated the example to reflect the current single region ability.
    * Instances now have the correct ssh parameters.
    * A Fleet API client.
    * Clean up on ssh tunnel code.