IDP03 unsolicited sso support

[Peter Schober]

* Alexander Galilov <alexander.galilov at gmail.com> [2015-05-07 17:50]:
> I changed AuthnRequestsSigned to false and got Shibboleth logon page by
> going to
> https://iis.authasas.local/idp/profile/SAML2/Unsolicited/SSO?providerId=https://authtest.my.salesforce.com

I still don't get it: If they so send authn requests why would you
continue to use IDP-initated SSO (where there are no authn requests)?
Anyway...
-peter