Fix OrderedDict usage for Python 2.6
Fix OrderedDict usage for Python 2.6

"import collections" also works on Python 2.6 but
collections.OrderedDict() is not available so the current check is
wrong. Using a function to get an OrderedDict() instance works fine for
that.

Closes-Bug: #1375568
Change-Id: Iaf739dc2deb7d4b09bf477be60de4df8c4fcf5c0
(cherry picked from commit 7212f7dc92c1c6fd5d7e36fc270b74efec412d72)

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