fix message refs

api/models/Message.js

@@ -3,8 +3,8 @@ const Schema = mongoose.Schema
 const message = new Schema(
     {
         body: String,
-        author: { type: Schema.Types.ObjectId, ref:'User'},
-        room: { type: Schema.Types.ObjectId, ref:'Room'},
+        author: { type: Schema.Types.ObjectId, ref:'users'},
+        room: { type: Schema.Types.ObjectId, ref:'rooms'},
         date: Date,
     }
 );