This recognizes migration type and executes either
        :method:`execute_python_migration` or :method:`execute_native_migration`

def execute_migration(self, migration_file_relative):
        """This recognizes migration type and executes either
        :method:`execute_python_migration` or :method:`execute_native_migration`
        """
        migration_file = os.path.join(self.db_config['migrations_dir'], migration_file_relative)
        m_type = self.repository.migration_type(migration_file)
        if m_type == 'native':
            return self.execute_native_migration(migration_file)
        if m_type == 'py':
            module = imp.load_source('migration_module', migration_file)
            return self.execute_python_migration(migration_file, module)
        assert False, 'Unknown migration type %s' % migration_file