Improve name of docker volume

[JasonGrace2282]

Proposed changes

• Add an explicit name to pgdata volume

Brief description of rationale

By default, docker prefixes volumes in a compose.yaml with the name of the folder it's in. For our case, that would make the volume called docker_pgdata. However, this means that any other project that has its docker compose in a folder called docker and doesn't give a special name to the pgdata volume will conflict with Ion.

Yes, this happened to me.

Things to consider

If there's any important data in the original volume, it may need to be copied over to the new volume.

[coveralls]

coverage: 79.073% (+0.08%) from 78.994%
when pulling 14680e0 on JasonGrace2282:docker-env
into f77b2df on tjcsl:dev.