Test for multiget and support for multiget ids

Add tests for multiget
Tolerate passing into the documents array
the ids of the documents as an alternative to
a document descriptor object.
Support for using a custom http.Agent

The Elasticsearch options support a parameter 'agent' that value
is undefined (default), false (no http polling) or
a custom instance of http.Agent

For example one could use this parameter with the
agentkeepalive (https://github.com/TBEDP/agentkeepalive)
to attempt to keep the http connection opened
Fixed closeIndex REST call

Change-Id: Ieda2faf7e6a37be8f916013981b0e0a88174b8a0
Merge pull request #76 from devoncrouse/master

Fixed closeIndex REST call
Revert "Merge pull request #76 from devoncrouse/master"

This reverts commit 2d744743aeca7deab9d81c55a26cfddb1120a8f5, reversing
changes made to 10403292aa3af456c7c7f8cd398573114db03d47.
Moved fixed _close test to the end so others don't failed on a closed
index, and implemented _stats API call + test

Change-Id: Ibefcf58d732b970f91bc3e999e7600eed3850710
Merge pull request #78 from devoncrouse/master

Moved _close test to end, and implemented _stats API call
Merge pull request #67 from hmalphettes/multiget

Test for multiget and support for multiget with an array of ids
Simple river, eg for mongodb
Merge pull request #83 from kersten/master

Simple river
Merge pull request #75 from hmalphettes/httpAgent

Support for using a custom http.Agent
incing package version. mostly to trigger tests.
Update indices.js

Fixing #90 & #76
Merge pull request #91 from phillro/rm90

Update indices.js
Update README.md
nginx requires a Content-Length=0 header for POST/PUT/DELETE