Port hide srvr addresses extension to v3 API Pt1

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: Ie3ca902f3e37328f59a164f15a790986b95c0155
Merge "Port hide srvr addresses extension to v3 API Pt1"