9.x BVT fails because mirror is not available

[Dmitry Mescheryakov]

See
https://product-ci.infra.mirantis.net/job/9.x.main.ubuntu.smoke_neutron/771/console
https://product-ci.infra.mirantis.net/job/9.x.main.ubuntu.bvt_2/772/console

Both fail at network verification step with
AssertionError: Task 'verify_networks' has incorrect status. error != ready, 'Repo availability verification failed on following nodes Fuel master node, slave-01_controller, slave-06_compute_ceph-osd, slave-04_compute_ceph-osd, slave-02_controller, slave-03_controller, slave-05_compute_ceph-osd.
 Following repos are not available - http://mirror.seed-cz1.fuel-infra.org/pkgs/snapshots/ubuntu-2017-01-16-030059/, http://mirror.seed-cz1.fuel-infra.org/mos-repos/ubuntu/snapshots/9.0-2017-01-16-104420.

[Andrey Nikitin (heos)]

The root cause of the problem is mirror.fuel-infra.org, because I've mistakenly disabled DHCP server in our public network. The mirror server had no static network configuration.
The bug is fixed by adding static network configuration to the server.