lua-socket-fix: fix for address resolving to localhost

it's uncertain which address bind/connect will choose when
connection to localhost. The problem is with /etc/hosts
which can contain bindings for both 127.0.0.1 and ::1 for
localhost (and some system don't).

See for futher explanation:
http://sourceware.org/bugzilla/show_bug.cgi?id=4980
lua-socket-fix: move resolver to coeio, add hostname numerical
address detection to sendto.
Merge branch 'lua-socket-fix'