Enforce ``saml2`` protocol in Apache config

Shibboleth, a SAML2 federation software should only protect urls with
protocol set to ``saml2``. Therefore, <Location> directive in the Apache
config should enfore this, instead of accepting every protocol.
Mind that a vhost should still accept all the protocols.

Change-Id: I0d368159fa8862581ae51267e6068f29cae942a2
Merge "Enforce ``saml2`` protocol in Apache config"