Sets the docker hostname option for dokku (https://github.com/progrium/dokku)
Currently just sets --hostname=${1} aka the project name. Give your project a FQDN. For use with interlock.
On the dokku server, you need to install the plugin in the standard Dokku way. Specifically:
cd /var/lib/dokku/plugins
git clone https://github.com/steigr/dokku-hostname.git
dokku plugins-install