Removed email from creation form

Removed e-mail field from form since it's not gonna be updated

Signed-off-by: Carlos Oliveira <carlospecter@gmail.com>
Signed-off-by: Sergio Oliveira <sergio@tracy.com.br>
Changed message for username validation

Signed-off-by: Carlos Oliveira <carlospecter@gmail.com>
Removed create_user method
Settings needs_update default to True
Allowing users to logout