Introduce Migration system for SQLite database

Hi Hackers,
We were looking at the migration pattern created for the SQLite database
and tried to look into the possibility of using a library that could handle
them for us.

- Migrations allow us to have a single path of creating the table instead
of creating tables using SQLAlchemy or hand rolled SQL. This pattern can
cause issues because updated databases might be different than the ones
created by SQLAlchemy
- The version numbering for the migrations is tedious and error prone.

After some research we found these 2 libraries(alembic, flask-migrate) that
can run migrations for us.

Alembic is a library written by the same person that wrote SQLAlchemy and
is used to manage and run the migrations.

Flask-migrate is the glue that joins Flask and Alembic allowing us to run
the migrations directly in the code.

What are your thoughts about this change?
Can we safely assume that everyone is in version 14 of the database?

--
Thanks
Joao & Sarah