Add IPv6 support

[chooper]

Add IPv6 support to elbping.

Note to resolve all.ipv6.[elbname] (IN AAAA) for node discovery

[chooper]

I've yet to need this so contemplating WONTFIX. Please comment if you're out there and need this.

[peralmq]

Hi @chooper, I'm gonna need it when iOS 9 hits the streets (in September?). http://www.internetsociety.org/deploy360/blog/2015/06/apple-will-require-ipv6-support-for-all-ios-9-apps/

[ckurban]

Hi @chooper I need this as Apple rejected my app because of IPv6 support, could you tell us when would it be fixed ?

[tmaier]

@ckurban and @perlamq, are you pointing directly to an IP address in your iOS apps? If you point to a domain, it should work and should not be rejected...

[ckurban]

Followed Apple guidelines for IPV6 testing and it works fine.

[shanthakumarf22]

still having issues getting ios app rejected for not having IPv6 support.. heroku doesn't support ipv6 yet?