Get the kapacitor URL.

def _get_url():
    '''
    Get the kapacitor URL.
    '''
    protocol = __salt__['config.option']('kapacitor.protocol', 'http')
    host = __salt__['config.option']('kapacitor.host', 'localhost')
    port = __salt__['config.option']('kapacitor.port', 9092)

    return '{0}://{1}:{2}'.format(protocol, host, port)