Reset password should not allow empty passwords (which can prevent the user to login anymore on the wiki)

Preconditions: an user U1 already exists and has a valid email set on its profile.

STEPS TO REPRODUCE

1. Click on Drawer, Login
2. Click 'Forgot your password'
3. Fill the username
4. Click 'Reset password'
5. Click on the link from the email received by the user
6. Fill some empty spaces on the 'New Password' and 'Re-enter New Password' fields
7. Click 'Save'

EXPECTED RESULTS

A hint is displayed below the 'New Password' and 'Re-enter New Password' fields informing the user that the password cannot be empty (warning like 'Password cannot contain only empty spaces').

ACTUAL RESULTS

The password is saved with empty spaces. Furthermore, the user cannot login on the wiki anymore, as it gets:

Error: No password given