Introduce havana initial state

This patch replaces folsom initial state and all migrations
from folsom to havana, with a new, configuration independent
initial db state, corresponding to the havana release.

In order to avoid large modules, "init ops" modules have been
created for all plugins, service plugins, and extensions.

Some migrations after the havana release were amended or
removed to reflect the new initial state being introduced.

Partially-implements: blueprint reorganize-migrations

Change-Id: I47bfd0d26fad1373013ae0d5716266ca40c493c6
Merge "Introduce havana initial state"