Gallery: Fix database creation on update, also only from version less then 0.5

apps/gallery/appinfo/update.php

 <?php
 
-$stmt = OCP\DB::prepare('DROP TABLE IF EXISTS *PREFIX*gallery_photos');
-$stmt->execute();
-$stmt = OCP\DB::prepare('DROP TABLE IF EXISTS *PREFIX*gallery_albums');
-$stmt->execute();
-
-\OC_DB::createDbFromStructure('./database.xml');
+$currentVersion=OC_Appconfig::getValue('gallery', 'installed_version');
+if (version_compare($currentVersion, '0.5.0', '<')) {
+	$stmt = OCP\DB::prepare('DROP TABLE IF EXISTS *PREFIX*gallery_photos');
+	$stmt->execute();
+	$stmt = OCP\DB::prepare('DROP TABLE IF EXISTS *PREFIX*gallery_albums');
+	$stmt->execute();
 
+	\OC_DB::createDbFromStructure(OC::$APPSROOT.'/apps/'.$appid.'/appinfo/database.xml');
+}