Made the weave-local domain "weave" a constant

Plus some logging on startup
Move timeout to incoming queries
Changed to accept a CIDR address and use net.IP

 * In general we'll have an IP address and a subnet mask for the weave
   network address; account for this in the zone DB and in the HTTP
   server.

 * Use the net.IP type rather than string, which gives us a bit more
   generality (in theory it'll deal with Ipv6 too) and validation (we
   attempt to parse the input)
Tidy up
Merge remote-tracking branch 'upstream/master'