core: squash 03_00_0000_add_schema_version.sql

This series of patches cleans the 3.0 specific upgrade scripts and
integrates it with the clean installation scripts.

3.0 configuration values are left as-is for backward compatibility.

Correctness of those patches was verified by comparing a database
created from scratch on the master with a database created from scratch
on the branch that includes those changes.

Change-Id: If9cae7423b57451edbd8a2e2ce4fc9ad225bd6b2
Signed-off-by: Eli Mesika <emesika@redhat.com>