chown issue

[bjornbouetsmith]

Hi,
I tried to install this on my docker container and use NFS shares a the location where all the data stored, i.e. the volumes, since I don't want them stored locally.

But cannot get it to work, since the container entrypoint.sh insists on doing:

chown "$BACKUPPC_USERNAME":"$BACKUPPC_GROUPNAME" /home/backuppc

Would you mind to create a variable for controlling whether or not any permissions should be set or not.

In fact it would be great if the entryppoint.sh could be configured to not create any users at all and simply require that a user has been set up before and just exit with that message if correct VARS has not been set before launching the container.

I am happy to submit a pull request, but I have never done any docker composes before.