Modify dumper script to include user, pass & host

[hieronymousch]

script should include the settings
PGUSERNAME=
PGHOST=
PGPASSWORD=
so it works with production environments

[ansuz]

Hi,
the author of this script is no longer with our company, and not running his own homeserver as far as I know, so this is unlikely to receive updates.

If you can make a PR for this issue I'll gladly accept it.

Thanks