remove MultipleResultsFound and NoResultFound exception
remove MultipleResultsFound and NoResultFound exception

these two exceptions are no longer used, let's remove them

Change-Id: I523d6e7ae062b4b0defca1d7b26c4898d14a2410

ityaptin/ceilometer,openstack/ceilometer,ityaptin/ceilometer,openstack/ceilometer