Process power state syncs asynchronously

The instance locking introduced in
cc5388bbe81aba635fb757e202d860aeed98f3e8 keeps the power state sane
between stop and the periodic task power sync.  However, locking on
an instance in the periodic task thread can potentially lock
that thread for a long time.

Fix this condition by executing power syncs in a background GreenPool.
Limit the syncs to 1 at a time per instance.

Closes-Bug: 1363231

Change-Id: Idbc00ddfcb7a6816433863ed1686ad8f7477d99b
Add new unit tests for PCI stats

These unit tests make sure that the stats pools are created and
ordered properly.

Partially Implements: blueprint pci-passthrough-sriov

Change-Id: I81591b18d1045a4451ce009b091b22875eb04890
Stash numa-related flavor extra_spec items in system_metadata

This is a temporary measure to avoid having to add additional persistence
of extra_specs data simply to facilitate merging the NUMA patches. Only
the numa_cpus.* and numa_mem.* items are saved from extra_specs at
this time. The expectation is that this will quickly come out in kilo
when the rest of the flavor information stashed in system_metadata gets
removed and stored elsewhere.

Blueprint: virt-driver-numa-placement
Change-Id: I83ca863d521c579d8f1fe6168d7b1096af9f14f1
Hook NUMA topology checking into claims

This patch adds the ability to test claims against NUMA topology exposed
by the host and instance. This is currently a no-op as no code in the
scheduler will actually attempt to set the limits against numa_topology.
Since getting the NUMA topology of the instance may require an additional
db roundtrip, we try to avoid getting it unless absolutely necessary.

This patch also changes the resource_tracker resize_claim method to
accept the image_metada of the instance as it is used (alongside flavor)
to calculate the new topology that will be exposed after the resize is
done.

The resource tracker will not do any actual usage tracking yet - this
will be done in a follow-up patch.

Blueprint: virt-driver-numa-placement
Change-Id: I07b690243d481c855c5e706f968cf224b336a1a0
Make resource tracker track NUMA usage

This patch makes the resource tracker actually track and update NUMA
usage from instance andd resize claims, and periodic resource updates.

Change-Id: Iea9d076cb37e530f442faefacd2a59b6b6225e92
Blueprint: virt-driver-numa-placement
Merge "Add new unit tests for PCI stats"
Merge "Process power state syncs asynchronously"
Merge "Stash numa-related flavor extra_spec items in system_metadata"
Merge "Hook NUMA topology checking into claims"
Merge "Make resource tracker track NUMA usage"