Volume will created always, also when it doesn't need

[rnz]

postgres/11/Dockerfile

Line 168 in 7e80419

VOLUME /var/lib/postgresql/data

When create multiple container with bind data directory for postgres, docker create volume if use this image based on this Dockerfile
Please add check ENV condition for create or not create volume.

same for other postgresql version

[wglambert]

Duplicate of #404