mandatory api limits
mandatory api limits

Co-Authored-By: Fabio Giannetti <fgiannet@cisco.com>
Co-Authored-By: Phil Neal <phil.neal@hp.com>

Change-Id: I6f3bc7758a699b7c69d5043036ddf07131b0d81e

openstack/telemetry-specs,openstack/ceilometer-specs