Configure network for FreeBSD servers

Summary:
This change offers a standard set of network definitions
for the pillar's nodes dictionary.

To allow several states to edit netif, use a folder instead
of a file (/etc/rc.conf.d/netif/jails, /etc/rc.conf.d/netif/…).

To parse the nodes dictionary, provide a node execution module.

Test Plan: Tested on Ysul where it creates correct files.

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1095