Issue 646 ckan api key

Fixes #643 
Take into account that both this and #703 are branching the alembic history, with should be linear, as they both share the same downgrade revision (or parent revision). The solution to this will be that right after any of the 2 is merged, it will turn to be the real parent of the other one (the one that have not been merged yet) and so we can keep a linear database migration history.