ES benchmarks

Summary:
usmanm@dev6:~/chronology/kronos (es)*$ ./runbenchmarks.py elasticsearch
> [elasticsearch]: running benchmark...
> [elasticsearch]: insert_throughput
  * 1 thread(s).
  - chunk_size=500 took 30.9670789242s
  - chunk_size=1000 took 22.2374238968s
  - chunk_size=5000 took 22.1717150211s
  - chunk_size=10000 took 22.3439631462s
  * 5 thread(s).
  - chunk_size=500 took 19.8991630077s
  - chunk_size=1000 took 19.8254759312s
  - chunk_size=5000 took 18.6680700779s
  - chunk_size=10000 took 19.4264819622s
  * 10 thread(s).
  - chunk_size=500 took 20.8147130013s
  - chunk_size=1000 took 19.2815799713s
  - chunk_size=5000 took 20.8605060577s
  - chunk_size=10000 took 20.6231579781s
> [elasticsearch]: read_size
  - read_size=5000 took 6.88117003441s
  - read_size=10000 took 5.41357588768s
  - read_size=15000 took 5.45154714584s
  - read_size=20000 took 4.87729001045s
  - read_size=25000 took 5.52102303505s
> [elasticsearch]: cleaning up...
> [elasticsearch]: took 401.175626993s

Test Plan: -

Reviewers: marcua, jblum

Reviewed By: jblum

Differential Revision: https://phabricator.locu.com/D7561