pollster trap error due to zero floating ip
pollster trap error due to zero floating ip

fixes bug #1056087 when nova doesn't have any
floating ip addresses defined causes a db
exception instead of raising it should be
trapped

Change-Id: Iea441fb8bcd720339b2446525a6202941c33a1ec

m1093782566/openstack_org_ceilometer,chungg/aodh,sileht/aodh,eayunstack/ceilometer,pkilambi/ceilometer,JioCloud/ceilometer,fabian4/ceilometer,NeCTAR-RC/ceilometer,rackerlabs/instrumented-ceilometer,fabian4/ceilometer,idegtiarov/ceilometer,shootstar/ctest,maestro-hybrid-cloud/ceilometer,idegtiarov/ceilometer,JioCloud/ceilometer,froyobin/ceilometer,redhat-openstack/ceilometer,citrix-openstack-build/ceilometer,pczerkas/aodh,rickerc/ceilometer_audit,r-mibu/ceilometer,rickerc/ceilometer_audit,Juniper/ceilometer,froyobin/ceilometer,tanglei528/ceilometer,rackerlabs/instrumented-ceilometer,redhat-openstack/ceilometer,m1093782566/openstack_org_ceilometer,citrix-openstack-build/ceilometer,citrix-openstack-build/ceilometer,Juniper/ceilometer,mathslinux/ceilometer,cernops/ceilometer,tanglei528/ceilometer,maestro-hybrid-cloud/ceilometer,pczerkas/aodh,chungg/aodh,mathslinux/ceilometer,rackerlabs/instrumented-ceilometer,isyippee/ceilometer,NeCTAR-RC/ceilometer,luogangyi/Ceilometer-oVirt,openstack/aodh,sileht/aodh,JioCloud/ceilometer,isyippee/ceilometer,shootstar/ctest,MisterPup/Ceilometer-Juno-Extension,MisterPup/Ceilometer-Juno-Extension,dreamhost/ceilometer,r-mibu/ceilometer,rickerc/ceilometer_audit,ityaptin/ceilometer,luogangyi/Ceilometer-oVirt,dreamhost/ceilometer,openstack/ceilometer,ityaptin/ceilometer,openstack/aodh,NeCTAR-RC/ceilometer,tanglei528/ceilometer,pkilambi/ceilometer,eayunstack/ceilometer,cernops/ceilometer,openstack/ceilometer