protected function storeUser(array $credentials, $activate = false)
    {
        $cred = array(
            'first_name'  => $credentials['first_name'],
            'last_name'   => $credentials['last_name'],
            'email'       => $credentials['email'],
            'password'    => $credentials['password'],
        );

        if ( array_key_exists('permissions',$credentials) )
        {
            $cred['permissions'] = $credentials['permissions'];
        }

        $user = $this->sentry->register($cred,$activate);

        if ( array_key_exists('groups',$credentials) )
        {
            $this->syncGroups($credentials['groups'], $user);
        }

        return $user;
    }