added alembic to requirements.txt
initialised alemic with connection string
Added first migration and changed make file to use Alembic
changed initial migration script to drop enums
reinstated logic from original clean script which is no longer called
changed metadata to BASE in Alembic env.py
Added pre clean for old schemas
Remove whitespace in Makefile
Add version numbers to requirements.txt
Merge pull request #113 from InsolvencyService/db-migrations

Alemic db migrations