elasticsearch: deploy shard percentage check

this is the initial deploy alongside the existing check to verify it works as
expected. Once that's validated we can switch over.
Judging from past alarms it would have fired a few times:

0.030303 2014-02 19:51
0.574468 2014-02 21:33
1.714290 2014-03 23:20
0.079008 2014-04 19:58
0.080046 2014-04 20:24
0.078593 2014-04 20:37
0.071414 2014-04 22:19
0.038087 2014-05 03:47
0.072611 2014-05 19:52
0.072611 2014-05 20:15
0.073936 2014-05 21:28
0.032132 2014-07 16:36

Change-Id: Ia83d2aa3f0e329e7212ad66c5e7d631f9f6ce939
Merge "elasticsearch: deploy shard percentage check" into production