Support browser password managers guess for username

[fogs]

Several modern browser implement their own password manager, allowing users to store username and password on locally. At least Mozilla Firefox and Google Chrome use the text input previous to the password field as best guess for the username. For the default registration form type in FOSUserBundle, this would be the email address. However, by default email addresses cannot be used as username when logging in.

I am aware, that I can override the default forms that are coming with the FOSUserBundle. But in my eyes, this should work nicely without having to change default settings.

The new order can be either

• username
• password
• password repeat
• email address

..or

• email address
• username
• password
• password repeat

..of which I have no preference.