user_saml: do not force login on neither special URLs nor CLI

When user_saml is configured to force users to log in, some URLs have to be excluded from the enforcement. These URLs are:

* `cron.php`
* `public.php`: authentication should not be required here
* `remote.php`: WebDAV clients and ownCloud sync clients will use Basic-Auth/Digest
* `status.php`

CLI works again when user_saml "force login" is set. It was showing some HTTP redirect stuff related to SAML authentication.