create-user: misc updates for Debian Stretch / server changes

Specify postgres host instead of assuming we are running on the
postgres server.

Use printf instead of "tee -i" to double output when setting initial
password; newer sudo barfs with permission denied on /dev/stdout (and
printf makes it clearer anyway).

Gitweb symlink creation was cruft, a cron on the webserver manages the
symlinks automatically.

And don't check for volume sync from outpost, it is not running
openafs-fileserver (just the afs db servers).