planemo/interactive fails to start

There seems to be an issue with the docker image wrt the startup script. I run the docker command:

`docker run -p 8010:80 -p 9009:9009 -v `pwd`:/opt/galaxy/tools -i -t planemo/interactive
`

and I get error messages:

```
umount: /var/lib/docker: must be superuser to unmount
Removing user `ubuntu' ...
Warning: group `ubuntu' has no more members.
Done.
groupadd: GID '0' already exists
useradd: group 'ubuntu' does not exist
passwd: unrecognized option '--stdin'
```

this is perhaps due to a change in the base image? Adding a group with gid 0 fails and then so does adding the ubuntu user to that group etc.