Can support wait for a moment before retries

https://github.com/elastic/elasticsearch-py/blob/1cae2b7eb0324c133be76a18e01a58d2b17485c0/elasticsearch/transport.py#L332

if attempt == self.max_retries:
    raise
else if self.retry_wait:
    time.sleep(self.retry_wait)

I use AutoSSH tunnel to connect to es, the network is sometimes unstable, will disconnect for a few seconds, and then automatically restore.

[fnavarrogonzalez]

A little improve over the solution of @vc1 could be instead of an linear retry, start with a lower value and increase it in every iteration (poly/exp).

[fxdgear]

Closed via https://github.com/elastic/elasticsearch-py/pull/794