Make password changing consistent

Steps to reproduce:
1. Go to Registration page and register a user
2. A validation_message will be displayed ( if the password is to short/ weak, or they don't match)

3. Go to Login page and click "Forgot your password"
4. Write your username and click "Reset password"
5. An email will be sent, go and reset the password by clicking the link in the email
6. The below reset form will be displayed ( add a space in the input an click save)

Results:
In the reset password form :
1. The password is saved even if only contains empty space ( A user could set an invalid password, an insecure one. )
2. No hints below password field are displayed, as for password fields in registration form