net: bind to `::` TCP address by default

Try binding TCP socket to `::` first before falling back to
`0.0.0.0`.
net: deduplicate Socket.prototype.address

Signed-off-by: Fedor Indutny <fedor@indutny.com>
fs: return blksize on stats object

Oversight to not pass blksize to fs.Stats on initialization.

Also added a test to make sure the object property has been set. Since
now on Windows both blksize and blocks will simply be set to undefined.