wrt Fig A in sstc-saml-bindings-2.0-draft-17

The "style" of Fig A in sstc-saml-bindings-2.0-draft-17 is different than the 
style being conjured up for -profiles-2.0-, fwiw.

I'm willing to fix-up the fig(s) in bindings to match that in profiles if folks 
think its ok to do so.

JeffH