IDP03 unsolicited sso support

[Peter Schober]

* Cantor, Scott <cantor.2 at osu.edu> [2015-05-07 15:55]:
> Salesforce *is* SP initiated, it works as well as any other bad
> implementation. I believe their metadata is broken and indicates
> it's going to sign the requests, but doesn't. That's certainly the
> cause of the error anyway, which should be pretty self-evident.

OK. I stopped at the first ERROR in the log and attributed that to
IDP-initated (also based on the first post in that thread, claiming
that the vendor does not send authn requests to the IDP, hence the OP
dabbling with IDP-initiated).
-peter