Lower pymongo dependency
Lower pymongo dependency

Debian has only 2.2, and there's no reason it wouldn't work according to
PyMongo changelog.

Change-Id: I4ca3d79aa1845ee513d93b25afaa0d41fab4bf59
Signed-off-by: Julien Danjou <5c682c2d1ec4073e277f9ba9f4bdf07e5794dabe@danjou.info>

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