Fix extension definitions

Before, extensions were missing the definition of mandatory methods.
At the moment, it's not a problem because the coding guidelines are not
enforced by the code. But in the future, it will break.
Now, extensions have all mandatory method definitions.

xExtension-KeepFolderState/extension.php

@@ -1,6 +1,16 @@
 <?php
 
 class KeepFolderStateExtension extends Minz_Extension {
+	public function install() {
+		return true;
+	}
+
+	public function uninstall() {
+		return true;
+	}
+
+	public function handleConfigureAction() {
+    }
 
     public function init() {
         Minz_View::appendScript($this->getFileUrl('jquerymin.js', 'js'),'','','');

xExtension-KeepFolderState/metadata.json

@@ -2,7 +2,7 @@
 	"name": "Keep Folder State",
 	"author": "Marco Heizmann",
 	"description": "Stores the state of the folders locally and expand them automatically if necessary.",
-	"version": 0.1,
+	"version": 0.2,
 	"entrypoint": "KeepFolderState",
 	"type": "user"
 }