fix getSiteMailer -> getSiteCapability update

accounts.js

@@ -182,7 +182,8 @@ function create(app) {
       };
       emailParams['h:Reply-To'] = emailParams.replyTo;
 
-      return req.getSiteCapability('email@daplie.com').sendMailAsync(emailParams).then(function () {
+      return req.getSiteCapability('email@daplie.com').then(function (mailer) {
+        return mailer.sendMailAsync(emailParams).then(function () {
           return {
             code_id: code.id,
             expires: code.expires,
@@ -190,6 +191,7 @@ function create(app) {
           };
         });
       });
+    });
 
     app.handlePromise(req, res, promise, '[issuer@oauth3.org] send one-time-password');
   };