parseMultiField() method signature change in es 1.4 and master

 As seen with elastic#7474, we need to update mapper attachment plugin with this new signature.

 Closes elastic#83.

src/main/java/org/elasticsearch/index/mapper/attachment/AttachmentMapper.java

@@ -269,7 +269,7 @@ public Mapper.Builder parse(String name, Map<String, Object> node, ParserContext
                         Map<String, Object> propNode = (Map<String, Object>) entry1.getValue();
 
                         Mapper.Builder<?, ?> mapperBuilder = findMapperBuilder(propNode, propName, parserContext);
-                        parseMultiField((AbstractFieldMapper.Builder) mapperBuilder, fieldName, (Map<String, Object>) fieldNode, parserContext, propName, propNode);
+                        parseMultiField((AbstractFieldMapper.Builder) mapperBuilder, fieldName, parserContext, propName, propNode);
 
                         if (propName.equals(name)) {
                             builder.content(mapperBuilder);