Additional glossary terms

Some additional terms from core we need to define along with some lousy
suggestions as a starting point, suggestions welcome. They are
interdependent definitions, because they sort of are a set of related terms.

name qualifier

A string that disambiguates an identifier that may be used in more than one
namespace to represent different principals.

namespace (in the federated sense, not the XML sense)

A domain in which an identifier is unique in representing a single
principal.

affiliation

A set of system entities that share a single namespace of identifiers for
principals.

I prefer this more limited definition for affiliation to the one in the
Liberty glossary, but maybe others disagree.

-- Scott