While these don't (yet?) get submitted to the Digitalocean marketplace, it should bring us most of the way of making that possible.
The next step would be to somehow get notifications of the new image snapshot sent... Somewhere and have the lovely DO folks test/release it for us.
This makes the installation a bit more secure by ensuring a user does not accidentally expose a way for unauthorized users to add new ssh keys to the system.
Additionally, this removes the extra HOSTNAME file to make the initial install process easier (that file was not modifiable by any dokku commands.
Closes#2247
