Untrack top.sls, move top.sls to top.sls.template
Support interface bonding, prepare for remote nodes

This is pretty big commit which completely reworks network configuration.
Nodes are much more flexible allowing configurations with bonding and
one interface. There is also initial network support for remote nodes
connected via openvpn.

New examples of ganeti pillar are included.
Merge pull request #1 from ffzg/network-rework

Network rework, untrack top.sls