Config: SimpleSAMLphp support (and SLO URL fixes)

Hi Bradley,

I have added support for a SimpleSAMLphp SP into our FR config and I thought I'd contribute the snippet into the default config file fr-config.groovy.example.

The endpoint URLs are as they are configured in a default SimpleSAMLphp config - and I've tested it with my own testbed - plus the same (manually entered) URLs are working in production with a real SimpleSAMLphp-driven website.

If interested, we have posted documentation on the SimpleSAMLphp SP install at https://tuakiri.ac.nz/confluence/display/Tuakiri/Installing+a+SimpleSAMLphp+SP (note: this page is still awaiting minor changes regarding SELinux config but is otherwise ready).

While testing this change, I found a weird issue in fr-config.groovy: the code snippets for shib23 and shib24 SP were listing the SLO redirect URLs with an extra "slo." in the Groovy namespace.

However, that got somewhere pruned as the config file was loaded _for these two_, but not for my own simplesamlphp entry.  So when testing the entry, my SLO Redirect entry for simplesamlphp was ignored, but the ones for shib23 and shib24 worked all fine.

Even when dumping the in-memory copy of the config (```grailsApplication.config.aaf.fr.knownimplementations.serviceproviders```), I would see that the entries for shib23 and shib24 got corrected but not the ones for my new addition.

I have corrected the entries for shib23 and shib24 as well (remove the extra ".slo") and all three entries now work all fine, but I could not figure out what was correcting them on the fly - so that grailsApplication.config.aaf.fr.knownimplementations.serviceproviders did not match the corresponding entry from fr-config.groovy.  Any idea about that?

And happy with the changes?

Cheers,
Vlad