feat(connection): attempt both ipv6 and ipv4 when no family entered (#260)
feat(connection): attempt both ipv6 and ipv4 when no family entered (#260)

If the user does not specify an IP family, we will attempt to
connect first via IPv6, and fall back to IPv4 if that fails

Fixes NODE-1222
mongodb/node-mongodb-native,mongodb/node-mongodb-native,mongodb/node-mongodb-native,mongodb/node-mongodb-native