Added some MANIFEST attributes to Ganymede client to prevent replay attack.

See http://docs.oracle.com/javase/7/docs/technotes/guides/jweb/no_redeploy.html
for full details on the purpose of the Permissions and Codebase attributes
we're adding to the ganymede.jar and ganymedeAdmin.jar manifests.

Basically, this change ensures that the newest Java runtime environments
will refuse to run our clients unless they are being downloaded from a
host on the same domain that they were built on.