Fix Game and add: Observer

src/main/java/it/polimi/ingsw/gc14/Network/Observer.java

@@ -0,0 +1,7 @@
+package it.polimi.ingsw.gc14.Network;
+
+import it.polimi.ingsw.gc14.Model.Game;
+
+public interface Observer {
+    public void update(Game model);
+}