Add pymeterpreter support for stdapi_net_resolve_host.

This PR adds support for stdapi_net_resolve_host and stdapi_net_resolve_hosts to the python meterpreter.  This works cross platform, it's been tested on Linux, OSX, Windows XP and Windows 7.  The AF_INET6 constant is different on Linux and Windows and this code expects to get the Windows value which is already use by post/windows/gather/resolve_hosts.  Only AF_INET and AF_INET6 are supported for the AI_FAMILY value.

To test use the post/windows/gather/resolve_hosts module, it works whether the session is Linux, OSX or Windows.