Mapping: attributes change to meta in 0.13

		I forgot to mention another breaking change in 0.13, so pinging the list to make sure people are aware of it. I have changed the name of the metadata that mappings can have from _attributes to _meta.If you are not familiar with the concept, here are the docs:Â http://www.elasticsearch.com/docs/elasticsearch/mapping/meta/.cheers,-shay.banon