Upgrade to elasticsearch 0.90.6

Incorporates the following changes:
https://github.com/elasticsearch/elasticsearch/issues/3653
https://github.com/elasticsearch/elasticsearch/issues/3680
https://github.com/elasticsearch/elasticsearch/pull/3837
https://github.com/elasticsearch/elasticsearch/commit/78af818d72a1c08663e15578a425f2534911b036

The testForceOverwrite test is broken since the output appears to be random.