core : Rest API operations Fail on oVirt-engine's logs

Authentication layer logs error message when
Session-TTL header was not passed

Change-Id: I88b28fffff075e00a7903f33198040bc95ba3900
Bug-Url: https://bugzilla.redhat.com/1121391
Signed-off-by: Ravi Nori <rnori@redhat.com>