No automatic tasks if the database is not created

The Enforcer NG is now using a database backend. This will trigger some new log messages before you have done the setup. Would it be possible to only start the automatic tasks once the setup has been done?

1. Only start the automatic tasks if the backend has been setup.
2. Start the automatic tasks once the setup has been done.
3. Remember to handle a second setup, so that we do not get multiple automatic tasks.

If you are starting with an empty database, then you get messages like:
Jan 10 16:31:57 ubuntu ods-enforcerd: [engine] enforcer started
Jan 10 16:31:57 ubuntu ods-enforcerd: SQLITE3: no such table: Policy (1)
Jan 10 16:31:57 ubuntu ods-enforcerd: expected to be able to select from table: Policy
Jan 10 16:31:57 ubuntu ods-enforcerd: [policy_resalt_task] unable to enumerate policies
Jan 10 16:31:57 ubuntu ods-enforcerd: [policy_resalt_task] retrying in 60 seconds
Jan 10 16:31:57 ubuntu ods-enforcerd: SQLITE3: no such table: EnforcerZone (1)
Jan 10 16:31:57 ubuntu ods-enforcerd: expected to be able to select from table: EnforcerZone
Jan 10 16:31:57 ubuntu ods-enforcerd: [enforce_task] zone enumeration failed
Jan 10 16:31:57 ubuntu ods-enforcerd: [enforce_task] retrying in 15 seconds
Jan 10 16:32:12 ubuntu ods-enforcerd: SQLITE3: no such table: EnforcerZone (1)
Jan 10 16:32:12 ubuntu ods-enforcerd: expected to be able to select from table: EnforcerZone
Jan 10 16:32:12 ubuntu ods-enforcerd: [enforce_task] zone enumeration failed
Jan 10 16:32:12 ubuntu ods-enforcerd: [enforce_task] retrying in 15 seconds