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-TTRSS_API/extension.php

@@ -1,6 +1,9 @@
 <?php
 
 class TTRSS_APIExtension extends Minz_Extension {
+	public function handleConfigureAction() {
+	}
+
 	public function init() {
 		$this->registerHook('post_update',
 		                    array($this, 'postUpdateHook'));

xExtension-TTRSS_API/metadata.json

@@ -2,7 +2,7 @@
 	"name": "TinyTinyRSS API",
 	"author": "Marien Fressinaud",
 	"description": "Provides an API compliant with TinyTinyRSS applications.",
-	"version": 0.1,
+	"version": 0.2,
 	"entrypoint": "TTRSS_API",
 	"type": "system"
 }