Create Vault url for token creation

def _get_token_create_url(config):
    '''
    Create Vault url for token creation
    '''
    role_name = config.get('role_name', None)
    auth_path = '/v1/auth/token/create'
    base_url = config['url']
    return '/'.join(x.strip('/') for x in (base_url, auth_path, role_name) if x)