Check interface is present in the VM

This patch enhances the method "wait_for_interface_status" from
tempest. Apart from checking the interface status returned by
Nova, this methods access the VM to check if the NIC interface
is already detected by the kernel.

Change-Id: I5e411c72e0b6a8d96535adb04ff15e903454141c
Closes-Bug: #1883095
3 files changed