Elasticsearch 5: Fix unreleased bugs in client

This commit fixes a bug in the Elasticsearch 5 transport client
binding. Namely, the update method was not indexing using the ID of the
read document, but instead the provided key. As auto-generated IDs are
used, this is a mistake as this is not the ID of the document. This
commit fixes this issue.

Additionally, the type is passed to the search method and used in
searches. While this is not a correctness issue per se, we fix it for
clarity.