Migrated to elasticsearch-py, the official ES client

this should provide more compatibility going forwards as well as
performance boost.
Patch fixes, thanks @robhudson!
Updated docs to use elastisearch-py
By default connect to localhost, not localhost:9200

9200 is http port that would break if thrift was requested for example
Forgotten 'when' in docs, thanks robhudson!
Update CHANGELOG re: elasticsearch-py