Use Socket.ip_address_list to get loopback addresses

[nateberkopec]

This will fix #1167

See JRuby bug

Need some guidance from @evanphx here: is binder supposed to bind to only loopback interfaces by default (as I've done in this PR) or is it supposed to bind to linklocal addresses as well?

Here's what this method returned before (my machine, CRuby):

["::1", "fe80::1%lo0", "127.0.0.1"]

Now:

["127.0.0.1", "::1"]

Note the omission of an ipv6 link-local interface. The reason I removed it was that there are several other link-local interfaces on my machine which I don't think puma should bind to:

irb(main):013:0> Socket.ip_address_list.select do |addrinfo|
irb(main):014:1* addrinfo.ipv6_linklocal?
irb(main):015:1> end
=> [#<Addrinfo: fe80::1%lo0>, #<Addrinfo: fe80::4b:c017:51b5:cd33%en0>, #<Addrinfo: fe80::989b:30ff:fe14:9e01%awdl0>, #<Addrinfo: fe80::f16e:6368:16b5:ff60%utun0>]

@evanphx if you can clarify the intent here, I'll add a test.

[nateberkopec]

Ah, I think I get it now. Linking #782.

[nateberkopec]

I'm also going to link #1022 here, because the original fix here caused that issue, maybe I can satisfy everyone.

[evanphx]

Looks good. When did Socket.ip_address_list show up? Do we need to be worried about ruby compat?

[nateberkopec]

Looks like it's in 1.9.3, so no.

[nateberkopec]

Also, JRuby returns the same result as CRuby does here, though it prints the full ipv6 address rather than the short ::1.