Use Ceph cluster stats to report disk info on RBD

Local disk statistics on compute nodes are irrelevant when ephemeral
disks are stored in RBD. With RBD, local disk space is not consumed when
instances are started on a compute node, yet it is possible for
scheduler to refuse to schedule an instance when combined disk usage of
instances already running on the node exceeds total disk capacity
reported by the hypervisor driver.

Change-Id: I9718c727db205b6f2191f8435583391584e96e6e
Closes-bug: #1332660
Signed-off-by: Dmitry Borodaenko <dborodaenko@mirantis.com>
Import Ironic scheduler filters and host manager

This is an import of the Ironic scheduler changes as of
commit da967d77894be6f23d81fb5cc948f9d13898ba84

implements bp: add-ironic-driver

Co-authored-by: Adam Gandelman <adamg@ubuntu.com>
Co-authored-by: ChangBo Guo(gcb) <eric.guo@easystack.cn>
Co-authored-by: Chris Behrens <cbehrens@codestud.com>
Co-authored-by: Chris Krelle <nobodycam@gmail.com>
Co-authored-by: Devananda van der Veen <devananda.vdv@gmail.com>
Co-authored-by: Fengqian Gao <fengqian.gao@intel.com>
Co-authored-by: Hans Lindgren <hanlind@kth.se>
Co-authored-by: Jenkins <jenkins@review.openstack.org>
Co-authored-by: Lucas Alvares Gomes <lucasagomes@gmail.com>
Co-authored-by: Michael Davies <michael@the-davies.net>
Co-authored-by: Rohan Kanade <openstack@rohankanade.com>
Co-authored-by: Zhongyue Luo <zhongyue.nah@intel.com>

Change-Id: I358d9c0485c5dcf81498871faa9150e3bf167c6b
Merge "Use Ceph cluster stats to report disk info on RBD"
Merge "Import Ironic scheduler filters and host manager"