This patch adds support for Linux Bridges to os-net-config. This is
done completely with ifcfg files, brctl is not used directly.
Hierarchy is preserved, so a Linux Bridge may have a Linux Bond
as a member, which in turn may have multiple interfaces as members.
This changeset has been updated to include a more specific example
for Linux bridge configuration (that doesn't combine bridging and
bonding).
This change depends on the change to add support for Linux Bonds.
Change-Id: I1ddacd514b02af30139a868071d82cde19b1f946
d01acefc15