Redirect the old join flow to the new one.

Once we confirm there are no troubles with the redirect, we can remove 
the code too.

src/routes.json

@@ -434,6 +434,12 @@
         "routeAlias": "/info/?(\\?.*)?$",
         "redirect": "/ideas"
     },
+    {
+        "name": "register-redirect",
+        "pattern": "^/accounts/standalone-registration/?$",
+        "routeAlias": "/accounts/standalone-registration/",
+        "redirect": "/join"
+    },
     {
         "name": "research-redirect",
         "pattern": "^/info/research/?$",