Include attachments in received facebook message

lib/Facebook.js

@@ -131,6 +131,7 @@ function Facebookbot(configuration) {
                                 timestamp: facebook_message.timestamp,
                                 seq: facebook_message.message.seq,
                                 mid: facebook_message.message.mid,
+                                attachments: facebook_message.message.attachments,
                             };
 
                             facebook_botkit.receiveMessage(bot, message);