Write Ansible tasks for feature generation

[conorsch]

The changes presented in #30 include strong documentation about the relevant setup tasks: https://github.com/freedomofpress/FingerprintSecureDrop/blob/f59a82f66c31fcdd040ffc48c35c0bc2c2466b9f/fpsd/test_db_setup.md

Run through that document and create Ansible tasks enforcing the state described. Both @fowlslegs and @redshiftzero should sign off on the new tasks, since they'll be altering database structure.