Config: fix SLO urls in sample config

The sample config fr-config.groovy.example was listing the SLO URLs
(for Shib SP 2.3 and 2.4) as:

          slo {
            artifact.uri = '$host/Shibboleth.sso/SLO/Artifact'
            slo.redirect.uri = '$host/Shibboleth.sso/SLO/Redirect'
            soap.uri = '$host/Shibboleth.sso/SLO/SOAP'
            post.uri = '$host/Shibboleth.sso/SLO/POST'
          }

Fix: remove the extra "slo." from the Redirect SLO URI
Config: Add SimpleSAMLphp SP to sample config

Add support for SimpleSAMLphp SP into sample config file
fr-config.groovy.example.

This config snippet lists the endpoints at URLs corresponding to a
default SimpleSAMLphp install.