Add extensible resources to resource tracker (2)

A resource plugin extension point is added to the resource
tracker to allow the types of resources allocated at the compute
node to be extensible. Information maintained by these plug-ins
is written to the compute_nodes table in the database. The
scheduler uses the information in the compute_nodes table to
determine scheduling decisions.

A plugin that implements vcpu resource tracking is included
and all other code for tracking vcpu has been removed. This
example ensures the plugins are tested in gate jobs.

This was previously merged and reverted due to a bug affecting
ironic CI. The bug was pre-existing but was exposed by the
that patch. This change is based on the bug fix here:
Icb19148660bca542a8120ecab064551d67ac28af and the previous
version of this change is here:
I64108338e3c958ba1276aaf113a68861cbe286f5

Co-Authored-By: Andrea Rosa  <andrea.rosa@hp.com>
Co-Authored-By: Paul Murray  <pmurray@hp.com>
This is part of: blueprint extensible-resource-tracking

Change-Id: If1381f99fd7db420380288faf7b2f57553f69136
makes sure correct PCI device allocation

With this patch, on the compute node, a stats pool will be associated with a
list of devices that belongs to the pool. This makes sure that PCI devices are
allocated out of the same stats pools that are used by the nova scheduler to
satisfy the PCI requests. And therefore, stats pools on the compute nodes will
be kept in sync with their counterparts in the nova scheduler.

Change-Id: I2d97c6354215e2ac5ff659e3203c33771abe1c09
Closes-bug: #1288809
Return 404 when floating IP pool not found

The FloatingIPPoolNotFound exception is raised only by the
Neutron integration API. When that happens, the exception
handling code should ensure a 404 response code is returned
in order to guarantee consistency with nova-network.

Change-Id: Id8ef7ee2c0d85f8b784b8d1d46c7120331f1e01a
Closes-Bug: 1353936
Merge "Add extensible resources to resource tracker (2)"
Merge "makes sure correct PCI device allocation"
Merge "Return 404 when floating IP pool not found"