title: Laravel 5.1 Authentication without password
body: <p>I'm developing an app in Laravel 5.1. I need to be able to login users only with e-mail (not using password). I have a password field in my login form because I need it for other reasons, but the only thing that I need to check is that the user email exists in my users table.
  I rewrited the AuthController, and I'm trying to use the attempt() method, but when i try to login with a valid e-mail, it gives me the following error: </p>
  
  <p>ErrorException in EloquentUserProvider.php line 112: Undefined index: password</p>
  
  <p>How can I tell to EloquentUserProvider that I'm not using password to login, only username (e-mail)?</p>
  
  <p>Thank you!!</p>