Look busy whilst requesting the email token

We need to wait for it to finish before letting the user start
completing the steps since if it fails, we can't complete the auth.

src/components/structures/InteractiveAuth.js

@@ -97,7 +97,7 @@ export default React.createClass({
             sessionId: this.props.sessionId,
             clientSecret: this.props.clientSecret,
             emailSid: this.props.emailSid,
-            requestEmailToken: this.props.requestEmailToken,
+            requestEmailToken: this._requestEmailToken,
         });
 
         this._authLogic.attemptAuth().then((result) => {
@@ -135,6 +135,19 @@ export default React.createClass({
         }
     },
 
+    _requestEmailToken: async function(...args) {
+        this.setState({
+            busy: true,
+        });
+        try {
+            return await this.props.requestEmailToken(...args);
+        } finally {
+            this.setState({
+                busy: false,
+            });
+        }
+    },
+
     tryContinue: function() {
         if (this.refs.stageComponent && this.refs.stageComponent.tryContinue) {
             this.refs.stageComponent.tryContinue();