Invalid postgres home directory (Debian, all versions)

[macropin]

The postgres user home directory is not specified when the user is created resulting in an invalid default of /home/postgres. Additionally the shell is not specified which results in a default bourne shell rather than the expected bash shell.

I propose we follow the Debian convention and set the home directory to /var/lib/postgresql and the shell to /bin/bash.

This will require modifying the useradd line in all the Dockerfiles as follows:

useradd -r -g postgres --uid=999 postgres -d /var/lib/postgresql -s /bin/bash

• See Altough the home directory of postgres user is /var/lib/postgresql, the owner is root. #274, where this is expected to be working.