Port extended status extension to v3 API Part 1

This changeset only copies the v2 implementation file into the
appropriate v3 directory 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 done 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.

Partially implements blueprint nova-v3-api

Change-Id: Ia5b80b70a7a459bf973de1c1aea8dc650e763b8d
Port Simple_tenant_usage API to v3 Part 2

This patch contains the changes required to adapt the Simple_tenant_usage
extension and the corresponding unittest to the v3 framework

Partially implements: bp v3-api-extension-versioning

Change-Id: I2db66704a77e822543e270773acc847267ef6ece
Merge "Port Simple_tenant_usage API to v3 Part 2"
Merge "Port extended status extension to v3 API Part 1"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp