Revert "Revert "Fix EUCA-7863 Support security tokens when authenticating S3 REST calls""

This reverts commit 618754214c90924821ebb540b5bdebef2a351399.
Fix use of security tokens with S3 - EUCA-7863

The WalrusRESTBinding now pulls the access key identifier from the
QueryIdCredentials of the authenticated user when available.

EUCA-7863
Record X.509 credential when used for walrus login - EUCA-7863

WalrusComponentLoginModule updated to record the certificate used for
authentication in the subjects public credentials. This addresses an
issue where a null credential value was used.

EUCA-7863