Update to Elasticsearch 1.0.0

With Elasticsearch 1.0.0 having been released a few days ago, it would be a good idea to update the module to work with 1.0.0.

So far on a test site, things have looked okay at first glance, but I haven't thoroughly tested it yet.

Breaking changes can be found here: http://www.elasticsearch.org/guide/en/elasticsearch/reference/1.x/breaki...