[security-services] Glossary

I reviewed the latest update to the Glossary that Eve provided a few weeks
ago.
Here are my comments / suggestions:
(1) Remove the terms related to (shared) sessioning (since it's not going to
be in SAML 1.0). Those include (in my view):
- Keep-alive
- Rich session
- Time-in
- Time-out
(2) Resource definition
Only keep (a) and (b), and relate to URI.
(3) Take out line 41 in Section 2 (Notation)
Marc Chanliau