allow index settings to be passed on index creation

src/helpers/create_index.js

@@ -22,10 +22,12 @@ const schema = {
   }
 };
 
-export default function createIndex(client, indexName, doctype = defaultSettings.DEFAULT_SETTING_DOCTYPE) {
+export default function createIndex(client, indexName, doctype = defaultSettings.DEFAULT_SETTING_DOCTYPE, settings = {}) {
   const indexBody = { mappings : {} };
   indexBody.mappings[doctype] = { properties: schema };
 
+  const body = Object.assign({}, { settings }, indexBody);
+
   return client.indices.exists({
     index: indexName,
   })
@@ -34,7 +36,7 @@ export default function createIndex(client, indexName, doctype = defaultSettings
       return client.indices.create({
         ignore: 400,
         index: indexName,
-        body: indexBody
+        body: body
       })
       .then(() => true);
     }