Store a random session key used to sign and verify comment ownership
once the database is initialized, not on every application startup.
Currently fixed session keys in [general] session-key are migrated into
the database on startup. The configuration parser will notice you about
the change and suggest you to remove this option.
When using Gunicorn or uWSGI to run `isso.dispatch` it would
automatically initialize and a default Isso instance (and cause
several logging messages), although never used.
If you use uWSGI or Gunicorn, you have to change the module from
`isso` to `isso.run`.
