Initialise the "jobs" table in the db.

def _init_jobs_table():
    """Initialise the "jobs" table in the db."""
    _jobs_table = sqlalchemy.Table(
        'jobs', _METADATA,
        sqlalchemy.Column('job_id', sqlalchemy.UnicodeText, primary_key=True),
        sqlalchemy.Column('job_type', sqlalchemy.UnicodeText),
        sqlalchemy.Column('status', sqlalchemy.UnicodeText, index=True),
        sqlalchemy.Column('data', sqlalchemy.UnicodeText),
        sqlalchemy.Column('error', sqlalchemy.UnicodeText),
        sqlalchemy.Column('requested_timestamp', sqlalchemy.DateTime),
        sqlalchemy.Column('finished_timestamp', sqlalchemy.DateTime),
        sqlalchemy.Column('sent_data', sqlalchemy.UnicodeText),
        # Callback URL:
        sqlalchemy.Column('result_url', sqlalchemy.UnicodeText),
        # CKAN API key:
        sqlalchemy.Column('api_key', sqlalchemy.UnicodeText),
        # Key to administer job:
        sqlalchemy.Column('job_key', sqlalchemy.UnicodeText),
        )
    return _jobs_table