This change moves our devstack plugin away from using the old
scheduling properties: memory_mb, local_gb and cpus. Nova will
stop using them for scheduling in Queens.
The cpu_arch property is left intact, as it's still useful.
The Placement API is polled to determine when nodes are fully exposed
to nova instead of polling the hypervisor stats. cURL + jq are used,
as the Placement OSC plugin is not ready yet.
Change-Id: I497a992bd86e8a359f333d6936621d1136d68061
fe2102f90c