Docker proc bump

In the process of getting `DockerProcessor` up and running again, it was necessary to update the `omero-process` image. A couple of questions:

 * Should I rework this to be on centos?
 * Is this actually `omero-py` rather than `omero-process`? `/opt/omero/bin/omero` does work.
 * ETA for omego release :) /cc @manics
I've run into a couple of uses:
 * pip installing a git branch
 * working with the source code
 * I have the feeling I needed it one more time but can't remember for what
 * I could also imagine wanting it for working with scripts, etc.