elasticsearch: handle request timeout and increase timeout

apparently requests doesn't do explicit max_retries on purpose, see
https://github.com/kennethreitz/requests/pull/1219 and
https://stackoverflow.com/questions/15431044/can-i-set-max-retries-for-requests-request

also increase timeout to something higher than a multiple of 3 as suggested
here: http://docs.python-requests.org/en/latest/user/advanced/#timeouts

Change-Id: I57f25489a46f46832b09a6e7dab6b1e72e82a87d