Run the pwiz introspector and get the models defined
        in the DB.

def get_pwiz_tables(self, engine, database):
        '''
        Run the pwiz introspector and get the models defined
        in the DB.
        '''
        introspector = pwiz.make_introspector(engine, database.database,
            **database.connect_kwargs)
        out_file = '/tmp/db_models.py'

        with Capturing() as code:
            pwiz.print_models(introspector)
        code = '\n'.join(code)
        # Unfortunately, introspect.getsource doesn't seem to work
        # with dynamically created classes unless it is written out
        # to a file. So write it out to a temporary file
        with open(out_file, 'w') as file_:
            file_.write(code)
        # Load up the DB models as a new module so that we can
        # compare them with those in the model definition
        return imp.load_source('db_models', out_file)