Generate 'network_config' in compatibility layer
Generate 'network_config' in compatibility layer

- generate 'network_config' object in the templates.py for
  mapping OpenStack networks on node interfaces in old-style tests.
- cases with BONDING=true will generate incorrect network_config;
  please use YAML template to describe such cases.
- add 'bootmenu_timeout' option for master node with USB.

Change-Id: I3702546f9d7d02fc17a4acc55ce5b3d85a2792da
blueprint: template-based-virtual-devops-environments

stackforge/fuel-devops,stackforge/fuel-devops