changed to using AuthenticaionUtil to get Subject, use the complete calling Subject from context
to invoke job, not the partially stored one

TODO: store principal(s) on JobDAO only; correctly implement authorization check using the stored
principal(s) and the current subject


git-svn-id: https://opencadc.googlecode.com/svn/trunk@702 728ff76a-78ac-11de-a72b-d90af8dea425