Fix an error of flawed logic in user.php fixes #40

If $this->roles is empty, either no roles where assigned, or all assigned roles were removed.

Only in that case, the code should look into a default value. 

The OR part in the if statement should not be there.

classes/warden/model/user.php

@@ -964,7 +964,7 @@ private function _ensure_and_validate_password()
   private function _add_default_role()
   {
     // Make sure no roles exist already
-    if (empty($this->roles) || !static::query()->related('roles')->get_one()) {
+    if (empty($this->roles)) {
       // Check for default role
       if (($default_role = \Config::get('warden.default_role'))) {
         $role = \Model_Role::find('first', array(