Add IPv6 support

[fancoder]

[clintar]

This will come with newer node.js support. You can use my modules I created pull requests for, but there are some other things needed for the pool to work with newer node.js. One thing I know of is the toByteArray function at https://github.com/clintar/cryptonote-universal-pool/blob/master/lib/pool.js#L20 to be used instead of the .toJSON() function. Haven't tested this code to see what else is needed. Oh, and another thing I remember is https://github.com/clintar/cryptonote-universal-pool/blob/master/lib/api.js#L732 to check for IPV6 localhosts.