Temporary fix empty messages diplay in conversation

These messages are events like nickname change.
The permanent fix will come from the facebook-chat-api library
Related issue: Schmavery/facebook-chat-api#313

index.js

@@ -176,8 +176,11 @@ function getFBThreadHistory(decoded, users, socket, threadID) {
 			return new Promise(function (resolve, reject) {
         currentUser.fbApi.getThreadHistory(threadID, 0, 10, '', function (err, data) {
           if(err) return console.error(err);
-					socket.emit('return/threadHistory', data);
-					resolve(data);
+          const filtered_data = data.filter(function(msg) {
+            return msg.body || msg.attachments.length > 0;
+          });
+					socket.emit('return/threadHistory', filtered_data);
+					resolve(filtered_data);
         });
 			});
 		})().catch(function(err) {