Allow multiple instances

[scollazo]

Feedback from @sevein in slack

Also perhaps you could try to revert the part where you add some additional named external volumes. I'm wondering maybe you'd only need to change their names, but it'd be nice to keep them as internal volumes. Otherwise you bring that extra cost of injecting the volume from outside the container. And in Docker for Mac that cost can be very high because the volume lives outside the VM that Docker for Mac runs internally. If that's for storing the database, the performance is going to be noticeably.

[sevein]

FYI: we've moved the dev environment to https://github.com/artefactual/archivematica/tree/qa/1.x/hack. Things that I would like to see happening if you still want to move this forward: 1) file a new issue describing the problem you're trying to solve, 2) find non-disruptive ways to introduce changes (e.g. don't change default port numbers like 62080), 3) update hack/README describing usage, 4) avoid adding external named volumes, and 5) submit PR against archivematica/artefactual. Thanks!