Generate default config file

def generate_config(directory):
    """
    Generate default config file
    """
    default_config = os.path.join(os.path.dirname(os.path.realpath(__file__)), "config.yml")
    target_config_path = os.path.abspath(os.path.join(directory, 'config.yml'))
    shutil.copy(default_config, target_config_path)
    six.print_("Config file has been generated in", target_config_path)