Ed: revert to add a sql script again

we changed the db update process to use alembic, but we need to keep the
sql migration scripts for the user using an old versioned old.

The user thus has to do:

source/script/update_db.sh settings.sh

--> to update the db schema to the alembic known schema

PYTHONPATH=. alembic stamp 35c20e6103d6

--> to tell alembic that the db is in the same version as the file
35c20e6103d6_create_tables.py

PYTHONPATH=. alembic upgrade head

--> to update the schema

NOTE: this has to be done only once, afterward only the alembic upgrade head is require
Ed: remove useless tables
Ed: remove useless indexes
Merge pull request #608 from antoine-de/add_sql_script

Add sql script