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.

CLI works again when user_saml "force login" is set.
Fix script name detection

Fixes the name detection when login enforcement is set. Works even when
ownCloud is installed on a subdirectory
Merge pull request #1877 from adoboPullRequests/user_saml_public_urls

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