When developing Dokku, it is useful to use a real domain to test actual functionality. This is impossible if the domain is hardcoded to dokku.me in testing.
When an app only has UDP ports exposed, deploys will fail as we expect there to be a single TCP port.
While we _should_ support both, the easier fix is to ignore things and move on. Users can manually expose UDP ports as necessary via the -p flag (or by not specifying the port as a UDP port).
One quirk discovered during tests is that disabling zero-downtime deploys results in odd output, but also a deploy can succeed even if one of the processes that skipped zero-downtime fails. We should fix this in another PR, but this is documented in tests for now.
Closes#4804
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
