CakePHP ElasticSearch plugin 2.0.0-RC2

• Improved fixtures handling
• Improvements to the Marshaller when having nested documents
• Improved FormHelper integration in the presence of nested documents
• Added IsUnique rule
• Added 'refresh' option when saving or deleting documents (In the save(), for example) to wait for the index to refresh before returning. See https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-refresh.html

Thanks to @josbeir for his awesome contributions.