Store Apps ina DB

[GiovanniSmokes]

Currently the apps are stored using file, we should change it to store in the postgres db.

[vporton]

@apssouza22 You have no objections to switch to SQL Alchemy before doing this issue?

We should do this, at least, to have a library for migrations. Working without migrations on a serious project is quite bad.

You didn't yet accept PR #52 - therefore, I ask you to avoid future merge conflicts: Should I switch to SQL Alchemy right in #52 (instead of a separate pull request that would conflict with #52) to which this issue is dependend?

[apssouza22]

Up to you.

I personally think that Migrations for projects that is not in production doesn't make much sense.

I need to test that PR again

[vporton]

I started to work rewriting the DB code in SQLAlchemy (with Alembic migrations). I didn't read the manuals of SQLAlchemy for a very long time, I am studying it anew.