stop using private timeutils attribute
stop using private timeutils attribute

the event api tests incorrectly reference a private attribute
from oslo_utils. this is not required and should not be done in
general. this patch changes this.

Change-Id: I03610078123edbe8ef89e8ea271d9c72ed4ba696
Closes-Bug: #1408737

ityaptin/ceilometer,chungg/aodh,mathslinux/ceilometer,Juniper/ceilometer,sileht/aodh,mathslinux/ceilometer,maestro-hybrid-cloud/ceilometer,r-mibu/ceilometer,chungg/aodh,idegtiarov/ceilometer,r-mibu/ceilometer,pczerkas/aodh,redhat-openstack/ceilometer,eayunstack/ceilometer,Juniper/ceilometer,redhat-openstack/ceilometer,isyippee/ceilometer,pkilambi/ceilometer,pkilambi/ceilometer,ityaptin/ceilometer,isyippee/ceilometer,pczerkas/aodh,maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,cernops/ceilometer,fabian4/ceilometer,idegtiarov/ceilometer,fabian4/ceilometer,cernops/ceilometer,openstack/ceilometer,sileht/aodh,openstack/aodh,openstack/ceilometer,openstack/aodh