DHCP server: windows support (and other distrs/OS as well)

[ameshkov]

Currently, it does not work as SetControlMessage returns error on Windows.

First of all, we should check if it's really necessary on Win. If it is, check if we can quickly add it: fancybits/go-net@5fe8124

[ameshkov]

I've subscribed to golang/go#7175, let's wait for them

[EugeneOne1]

The only unsupported OS since 506b459 is Windows. We should probably look if we can now enable Windows support in a future version.

[ngorskikh]

Please add DHCP on Windows.
I can't be the only one who is too cheap to buy a router and uses hostednetwork instead :)
The OS-provided DHCP is, unfortunately, of excremental quality.