Replace {} with null to be compliant with newer specs. While older also accepted null for the auth part of the registration request object

Took 18 minutes

src/components/structures/auth/Registration.js

@@ -243,7 +243,7 @@ export default createReactClass({
             });
         };
         try {
-            await this._makeRegisterRequest({});
+            await this._makeRegisterRequest(null);
             // This should never succeed since we specified an empty
             // auth object.
             console.log("Expecting 401 from register request but got success!");