add package exercice7

add class Action, Button

src/main/java/fr/unantes/l3/construction/exercice7/Action.java

+package fr.unantes.l3.construction.exercice7;
+
+public class Action {
+}

src/main/java/fr/unantes/l3/construction/exercice7/Button.java

+package fr.unantes.l3.construction.exercice7;
+
+public class Button {
+}