packaging: setup: reusable postresql provisioning

took the simple approach... each installer will use provisioning as-is,
it may cause postgres multiple restarts and such, but it keeps loosely
coupled components.

Change-Id: Ieff824fa5115954925f8fd7cabf59d535f39e96c
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>