fix column name and alignment
fix column name and alignment

3rd column of measurements table should be Unit.
And alignment should be left.

Change-Id: Ic7e7e7264bb7b4dfe7949f781d23dcba7db71604

luogangyi/Ceilometer-oVirt,pczerkas/aodh,fabian4/ceilometer,NeCTAR-RC/ceilometer,froyobin/ceilometer,openstack/aodh,froyobin/ceilometer,mathslinux/ceilometer,redhat-openstack/ceilometer,maestro-hybrid-cloud/ceilometer,redhat-openstack/ceilometer,isyippee/ceilometer,luogangyi/Ceilometer-oVirt,idegtiarov/ceilometer,sileht/aodh,eayunstack/ceilometer,fabian4/ceilometer,pkilambi/ceilometer,MisterPup/Ceilometer-Juno-Extension,ityaptin/ceilometer,m1093782566/openstack_org_ceilometer,pczerkas/aodh,chungg/aodh,cernops/ceilometer,openstack/ceilometer,MisterPup/Ceilometer-Juno-Extension,ityaptin/ceilometer,openstack/aodh,chungg/aodh,tanglei528/ceilometer,isyippee/ceilometer,r-mibu/ceilometer,Juniper/ceilometer,r-mibu/ceilometer,NeCTAR-RC/ceilometer,pkilambi/ceilometer,Juniper/ceilometer,tanglei528/ceilometer,cernops/ceilometer,idegtiarov/ceilometer,maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,mathslinux/ceilometer,sileht/aodh,NeCTAR-RC/ceilometer,openstack/ceilometer,m1093782566/openstack_org_ceilometer,tanglei528/ceilometer