Fix fixed-ip schema for empty response body

Nova had bug#1356058 for response of reserve/unreserve fixed ip APIs,
where plain text ("202 Accepted The request is accepted for processing.")
was returned in response body.

It is fixed on Nova side - Ifca3081f573407808a2196e71ac1db87180db6ec
So this commit fix the response schema for those APIs.
Also rename schema as per API operations it is used for.


Change-Id: I098ee0d1fa3056f8cfb0654e2b8fd3bf75fb3e2c
2 files changed