Add tests of fixed_ips in the attach interfaces nova API

The attach interfaces API of nova does not specify port_id or
fixed_ips in tempests.
So, need to check these behavior in tempests.

This patch include test case of fixed_ips.

Change-Id: I88e1960a5706b00d37e79ce93cb86a62420ae0fa
Closes-bug: #1525813
1 file changed