Ensure craue_config_setting migration are ok

We now can run the migration every time, new line from `craue_config_setting` are properly checked.

app/DoctrineMigrations/Version20161031132655.php

@@ -29,6 +29,13 @@ class Version20161031132655 extends AbstractMigration implements ContainerAwareI
      */
     public function up(Schema $schema)
     {
+        $images = $this->container
+            ->get('doctrine.orm.default_entity_manager')
+            ->getConnection()
+            ->fetchArray('SELECT * FROM '.$this->getTable('craue_config_setting').' WHERE name = "download_images_enabled"');
+
+        $this->skipIf(false !== $images, 'It seems that you already played this migration.');
+
         $this->addSql('INSERT INTO "'.$this->getTable('craue_config_setting')."\" (name, value, section) VALUES ('download_images_enabled', 0, 'misc')");
     }