Removed appu command in favor of direct docker run

The appu command was responsible for creating the config file required
by the appu container, as well as downloading and preparing the files
to be mounted. Then, the appu command was running the appu container.

The files preparation are now responsibility of the epidator file,
which now also creates the episode YAML file. Then the appu container
can be run with the docker run command as documented in the README
file.