[wsrp] UserContext caching

Relative to the discussion on the Interfaces
SC call today, the relevant statement in the spec (5.1.15) is "Note
that the Consumer MAY send UserContext
information on any invocations as a replacement for information the Portlet
MAY be storing in a session".
I understand this to say that when the Consumer has a change to the cached
UserContext it sends the entire UserContext.

Rich