Adjusted proxy-granting ticket retrieval steps.
Adjusted proxy-granting ticket retrieval steps.

Previously, tickets were retrieved using the ServiceTicket#pgt method;
however, because PGTs can only be accessed once and thus constitute a
non-idempotent and irreversibly mutative operation on ServiceTickets, I
decided it made more sense to reflect this fact in the ServiceTicket
API.  The added step doesn't seem to be particularly arduous.

NUBIC/castanet