appletviewer should allow some sun.* packages

Currently, the appletviewer does not permit loading of any sun.*
packages for security reasons. This seems a little bit of overkill,
and a little bit presumptious of one group inside Sun to say that
no part of Sun should ship applets.

How about changing the restriction to some some-domain like
sun.private.*, sun.java.*, sun.jpb.* or some more limited part of the
name space.