Implemented wonder class and interface

server/core/src/main/java/fr/univnantes/software_engineering/wonder/IWonder.java

+package fr.univnantes.software_engineering.wonder;
+
+public interface IWonder
+{
+    /**
+     * Upgrade the current wonder
+     */
+    void upgradeWonder();
+
+    /**
+     * Calculate Wonder victory points based on the wonder stage
+     *
+     * @return
+     */
+    int calculateVictoryPoints();
+}

server/core/src/main/java/fr/univnantes/software_engineering/wonder/Wonder.java

+package fr.univnantes.software_engineering.wonder;
+
+public class Wonder implements IWonder
+{
+    /**
+     * Upgrade the current wonder
+     */
+    @Override
+    public void upgradeWonder()
+    {
+
+    }
+
+    /**
+     * Calculate Wonder victory points based on the wonder stage
+     *
+     * @return
+     */
+    @Override
+    public int calculateVictoryPoints()
+    {
+        return 0;
+    }
+}