merge caas storage into s3 backend

src/storage/filesystem.js

@@ -143,7 +143,8 @@ function testConfig(apiConfig, callback) {
     });
 }
 
-function backupDone(backupId, appBackupIds, callback) {
+function backupDone(apiConfig, backupId, appBackupIds, callback) {
+    assert.strictEqual(typeof apiConfig, 'object');
     assert.strictEqual(typeof backupId, 'string');
     assert(Array.isArray(appBackupIds));
     assert.strictEqual(typeof callback, 'function');