Proposal for WI#13 Optional Target Elements

Actually this is more of a declaration that I will champion this issue,
since I think the description is pretty complete:

13. Optional Target Elements

   Make Subjects, Resources, Actions elements optional in a
   Target.  Missing element has same semantics as <Any.../>
   Make Target itself optional.  Missing element has same
   semantics as a Target containing <AnySubject/>,
   <AnyResource/>, <AnyAction/>.

   TYPE: Simplicity of policy construction
   STATUS: Needs proposal.
   PROPOSAL:
   CHAMPION: Hal Lockhart
   F2F: No

The only change I would suggest is that any new target elements we add
should get the same treatment.

Actually I thought we already made Target optional because of the case of
nested policies and policy sets.

Hal