Show terms and privacy policy if FxA is enabled (bug 1033851)

Add the terms and privacy policy links on create-pin if FxA is enabled (based on the data attr)

![firefox_os_simulator](https://cloud.githubusercontent.com/assets/1514/3937583/10baacec-24af-11e4-9acc-b383b8874fdb.png)

It gets dismissed as soon as you type a char or cause an error (so there's room for the error).