Make firestack(__, name) param optional until it's implemented

Author: BlooJeans

lib/firestack.js

@@ -34,7 +34,7 @@ export default class Firestack extends Singleton {
    * @param options
    * @param name - TODO support naming multiple instances
    */
-  constructor(options: Object, name: string) {
+  constructor(options: Object, name?: string) {
     const instance = super(options);
 
     instance.options = options || {};