alembic with initial migration and tests

All sqlalchemy migrations and code associated
with them was removed including tests

Added all necessery alembic code to expose alembic specific features:
like revision and stamp

Added initial migration for alembic, that is fully in sync with models
including: uniques, indexes and columns params

Refactored test_versions to use alembic as migration api

Refactored BaseTestCase and Database fixture to use alembic as migration api

Change-Id: I8a91704d21ccea1b8135b9d724df5856ac21108c
Merge "alembic with initial migration and tests"