Sync requirements with os/requirements

Change-Id: I420180311f0b40e2cd7307697d3c8eb4471a873d
Sync oslo with os/oslo-incubator

pyXX compatibility improvements
rpc-related bug fixes

Change-Id: I42576e58efced3b241476c23b4ffb5e5cf202c3e
Merge "Sync oslo with os/oslo-incubator"
Merge "Sync requirements with os/requirements"