elasticsearch sniffing support?

[pingz]

The elasticsearch-py documents recommend turn on sniffing when application is long-running to make sure client is aware of the changes about the cluster location. I think it is worth trying to support it.

ref: https://elasticsearch-py.readthedocs.io/en/master/#sniffing

[cmanaha]

Makes sense; Setting it as an extra parameter with default to true seems the way to go.
One for next iteration or if anyone would like to pick up that PR.

[pingz]

@cmanaha thanks for your reply, I've opened PR #42 , would you be kind enough to review it?

[cmanaha]

Commented on the PR; Hopefully this weekend or the next I'd like to spend some time merging all changes, running tests and checking if there is any additional test we should do (in regards to sniffing). Thanks a lot for your PR's !