Add a toString method to the Daily model (#19)

backend-services/feed-service/app/models/Daily.scala

@@ -31,4 +31,7 @@ object Daily {
     def getAllDailies(): Future[Seq[Daily]] = {
         dailyRepo.getAllDailies()
     }
+
+    def toString(daily: Daily): String =
+        return s"Daily(${daily.id.toString()}, ${daily.userId.toString()}, ${daily.questionId.toString()}, ${daily.content}, ${daily.likes})"
 }