Notification support for host aggregate related operation

Add notification for the following operations related to host
aggregation:
1) Send notification when create a new host aggregation
2) Send notification when delete a host aggregation
3) Send notification when add host to a host aggregation
4) Send notification when delete host from host aggregation
5) Send notification when update host aggregation for aggregate
name and available zone
6) Send notification when update host aggregation meta data

Change-Id: I2dc42addb587c4765b41e464697f35b1f844fde9
Implements: blueprint notification-host-aggregate
port Instance_usage_audit_log  API into v3 part1

This changeset only copies the v2 files into the appropriate v3
directories unchanged. The copy as-is will not be loaded by either
the v2 or v3 extension loaders. The second changeset will then
make the changes required for it to work as a v3 extension.

This is being tried in order to make reviewing of extension
porting easier as gerrit will display only what is actually
changed for v3 rather than entirely new files.

Change-Id: I671ee9b3a0061195e9f387d60a63f74acb36bbfa
port Instance_usage_audit_log API into v3 part2

This port Instance_usage_audit_log api into v3.

Partially implements: bp v3-api-extension-versioning

Change-Id: Ia76b00e167c8d4514799e825e48031e45e290ed4
Use oslo.sphinx and remove local copy of doc theme

Use the new oslo.sphinx version of the OpenStack doc
theme instead of copying it into this repo.

blueprint oslo.sphinx

Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>
Change-Id: I0bd91f7bb43f97b99051fed65b75fc05d5149cc8
Merge "Notification support for host aggregate related operation"
Merge "port Instance_usage_audit_log  API into v3 part1"
Merge "port Instance_usage_audit_log API into v3 part2"
Merge "Use oslo.sphinx and remove local copy of doc theme"