Refactor: move strategies in a package, other minor modification

src/notificationSendingStrategies/FastSendNotificationStrategy.java

@@ -0,0 +1,8 @@
+package notificationSendingStrategies;
+
+public class FastSendNotificationStrategy implements SendNotificationStrategy {
+    @Override
+    public String makeContent(String message) {
+        return message;
+    }
+}