#4 Add a close() method to iterators

[Brian Schlosser]

Need to add a close() method to iterators so resources
can be freed.

Example:

Client gets an instance iterator that is connected of
CIMXML to a provider that is iterating from a database.
Say there is some large number of instances, but after
the 3rd instance the client got what is needed. With
the current impl, the client has to complete iterating
before the connection will be closed, or close the
client which will cause all connections to be closed. A
close() method would allow just the connection for the
iterator to be closed. On the server side when the
connection is closed the provider needs to be notified
so that it can release it's database resources, the
close() method would also facilitate this.