TODO comments on the registration flow

Add some notes to Signup and the Registration component that it would be nice
to factor out some common code someday.

src/Signup.js

@@ -54,6 +54,9 @@ class Signup {
  * This exists for the lifetime of a user's attempt to register an account,
  * so if their registration attempt fails for whatever reason and they
  * try again, call register() on the same instance again.
+ *
+ * TODO: parts of this overlap heavily with InteractiveAuth in the js-sdk. It
+ * would be nice to make use of that rather than rolling our own version of it.
  */
 class Register extends Signup {
     constructor(hsUrl, isUrl, opts) {

src/components/structures/login/Registration.js

@@ -28,6 +28,10 @@ var CaptchaForm = require("../../views/login/CaptchaForm");
 
 var MIN_PASSWORD_LENGTH = 6;
 
+/**
+ * TODO: It would be nice to make use of the InteractiveAuthEntryComponents
+ * here, rather than inventing our own.
+ */
 module.exports = React.createClass({
     displayName: 'Registration',