Support Windows on node >= 0.11.14

Clustering dgram sockets isn't supported on Windows, and can't be
disabled until node 0.11.14. When dgram is clustered, node crashes.
After 0.11.14 we can request dgram sockets not be clustered by using the
new exclusive option to bind.

cf. joyent/node#8643

/to @rmg still in the process of building node on Windows to prove this works, will PR to you after I do
/cc @chandadharap