[wsrp] Spec defined events

I was reminded this AM of a couple of
possible events we have discussed in the past:

ProducerMetadataChanged - Notification
that the Producer's metadata has changed. The Consumer may want to refresh
its cached info.

PortletMetadataChanged - Notification
that the Portlet's metadata has changed. The Consumer may want to refresh
its cached info.

AvailablePortletsChanged - Notification
that the Producer has changed the set of portlets exposed via WSRP. Event
payload should indicate the type of change (added, deprecated, deleted),
the portletHandle of the subject portlet and the portlet's title.

Rich