systemd.networkd support

[Sjd-Risca]

Since Stretch the use of network configuration with systemd-network is getting more and more used.
Has any body already tried to support it?

For references: https://www.freedesktop.org/software/systemd/man/systemd.network.html

[aboe76]

you might take a look at https://github.com/aboe76/systemd-formula

I have just asked salt-formulas to take it..