[elasticsearch] Add timeout to API calls

Summary:
Default of 300 seconds is more than likely too much in most cases.
Provide the option to override.

Test Plan:
Blocked ElasticSearch with iptables
Set timeout to 5 seconds and make sure we error early

Reviewers: epriestley, vrana

Reviewed By: vrana

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D2678