Generate ssh-hostkeys on boot for ironic agent
Generate ssh-hostkeys on boot for ironic agent

Ironic agent images should have ssh hostkeys in image on boot.

Change-Id: If8d42bb8b8bff417d5b1d4d8bc371425697edde5
Closes-Bug: #1556145

openstack/diskimage-builder,openstack/diskimage-builder,switch-ch/diskimage-builder,switch-ch/diskimage-builder