use $resource class methods to avoid sending whole model to server & reduce some responses

src/controllers/groups.js

@@ -218,17 +218,11 @@ api.postChat = function(req, res, next) {
     user.save();
   }
 
-  async.series([
-    function(cb){
-      group.save(cb)
-    },
-    function(cb){
-      populateQuery(group.type, Group.findById(group._id)).exec(cb);
-    }
-  ], function(err, results){
+  group.save(function(err, saved){
     if (err) return res.json(500, {err:err});
-    res.json(results[1]);
-  })
+
+    res.json({message: saved.chat[0]});
+  });
 }
 
 api.deleteChatMessage = function(req, res){