When using the multiple nic-config templates in THT
and in tripleo-ansible the ordering of networks in
the network_data file matters.
Add and 'idx' key internally so that we can put a tag
on neutron network resources to keep track of the
ordering.
NOTE: Now also rename unused 'net' variable to '_'.
Change-Id: I6162ee854b08668274df32120e3ffc961b6cf807
Partial-Implements: blueprint network-data-v2-ports
(cherry picked from commit ff52ddb391)
4877a81a47