SAML 1.1 SSO sketched out

[Cantor, Scott]

I have the run-through of the web flow for the simplest profile we have
sketched out:

https://wiki.shibboleth.net/confluence/display/IDP30/SAML+1.1+Browser+SSO

There are a number of design questions, mostly needing discussion with
Brent once he's back from vacation, but a lot of the code is already there
from Chad's work and just needs cleanup.

Error handling is also TBD, but I have it in mind.

SAML 2 will be pretty similar but has some extra steps. ECP should be a
copy of that with some additional actions added.

Attribute query and artifact lookup are probably just as simple as this
one, but I haven't looked into the differences for a back-channel case yet.

-- Scott