[CRITICAL] Docker volume won't allow updating

[Hobadee]

Currently the Docker volume is set to /opt/cometd/. This is too greedy. (My fault. Still new-ish to Dockerfiles and didn't think out the ramifications.) Since that folder contains the binaries, updating won't work properly since they will be stored in the volume.

This will be a bit ugly to pick apart, as it likes to have everything in the same folder. Perhaps symlinks will fix the issue, or we may need to figure something else out.

We should also keep in mind current users (coughmecough) who will need to upgrade, and how whatever fix is determined will be applied so data isn't lost.