DERBY-3476: Improve serialization of DatabasePermission

Store the URL only once (remove the url field, as the URL is already
stored in Permission.name).

Make the pathType field transient, since it is recalculated on
deserialization anyway.

Store the actions portion of the permission.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1609039 13f79535-47bb-0310-9956-ffa450edef68