ifdown: Use new methods to create NIC files
ifdown: Use new methods to create NIC files

NIC files containing corresponding tap name are created during:

* instance startup
* NIC hot-add

For compatibility we continue creating indexed based NIC files along
with uuid based ones.

Signed-off-by: Dimitris Aragiorgis <4514117c4a99256e19437c7e3407c4ecbf98aec0@grnet.gr>

apyrgio/snf-ganeti,apyrgio/snf-ganeti