Make methods static where possible (except openstack.common)

Change-Id: I68b3eef29359e39755f3f62debc06918635d73b2
Synchronize Python 3 requirements

We missed a few requirements in Python 3, which breaks installing
Ceilometer in Python 3 environment and therefore breaks Gnocchi.

Change-Id: I0fa6f5cad00eb3d5a645216bd96b4bba55417f88
Merge "Make methods static where possible (except openstack.common)"
Merge "Synchronize Python 3 requirements"