v0.6.2
	- update multi search `[]` method to raise an exception with key name to
	make it easier to debug failed queries within a multi search hash.
v0.6.0
	- Change documents to be able to define indexes with multiple doc types.  A
	Document class can define subclasses which are of different doc_types and
	all live in the same index's mappings.
	- updated search queries to pass either a list of document types or a single
	document type.
	- Update documents to generate a default document_type from the class name
	so that Documents always have a document type. You'll still usually want to
	manually define the document type, but it's no longer necessary.
v0.5.2
  - Add aggregations to multi_search
v0.5.1
  - Add ability to reindex individual attributes of a document using the
  bulk_update API.
v0.5.0
	- Refactor of multisearch and search facade
	- add Search::Results proxy object so pagination and meta data methods can
	be standardize across all responses
  - Searches no longer return a simple array, they now return the
  Search::Results object which proxies array and is enumerable.
v0.4.5
  - Fix issue with hash strings and pagination
v0.4.4
  - Added support for surfacing document _score on query results.