Update to elasticsearch 1.2.0

Closes elastic#66.
(cherry picked from commit fb3b288)

Author: dadoonet

README.md

@@ -6,6 +6,7 @@ The mapper attachments plugin adds the `attachment` type to Elasticsearch using
 In order to install the plugin, simply run: `bin/plugin -install elasticsearch/elasticsearch-mapper-attachments/2.0.0`.
 
 * For master elasticsearch versions, look at [master branch](https://github.com/elasticsearch/elasticsearch-mapper-attachments/tree/master).
+* For 1.2.x elasticsearch versions, look at [es-1.2 branch](https://github.com/elasticsearch/elasticsearch-mapper-attachments/tree/es-1.2).
 * For 1.1.x elasticsearch versions, look at [es-1.1 branch](https://github.com/elasticsearch/elasticsearch-mapper-attachments/tree/es-1.1).
 * For 1.0.x elasticsearch versions, look at [es-1.0 branch](https://github.com/elasticsearch/elasticsearch-mapper-attachments/tree/es-1.0).
 * For 0.90.x elasticsearch versions, look at [es-0.90 branch](https://github.com/elasticsearch/elasticsearch-mapper-attachments/tree/es-0.90).