CAS-1238 Ensure authentication in ticket assertion satisfies sec policy.

The "primaryAssertion" field in the assertion must contain the
authentication event that satisfies security policy in order to support the
use case where the ticket validation response contains information to
indicate security policy was satisfied.

SuccessfulHandlerMetaDataPopulator provides a simple means to support
sending back handler names in the ticket validation response which could be
the basis of a simple policy check on the client side.