Compact pre-Icehouse database migrations <= 190.

Compacts the pre-Icehouse database migrations <= 190 into a
single migration (190_havana.py).

Pre-Icehouse users will now need to upgrade to Havana before
running any Icehouse migrations.

Tested on MySQL and PostgreSQL schemas on Fedora 19 to ensure the
new compacted migration generates an identical schema to the
previous migrate scripts in Havana.

Specific changes include:

 1) Drop migrations 181 - 184 which synced up shadow table changes.
   We now accomodate these changes in the base migration.

 2) Rename unique contraints per 185_rename_unique_constraints.py

 3) Add a new BDM table format.

 4) Add instance groups tables.

 5) add reason column to service

 6) add cells unique constraint

 7) add security groups unique constraint

Change-Id: Ibf2289f37c2376f3bd564728db5400859523c619
Implements: blueprint compact-havana-db-migrations
Merge "Compact pre-Icehouse database migrations <= 190."