Fix connection issues in 0.11.0 release

[maeldur]

Trying to address issue #632, I believe this commit 9c68a28 broke the ability to connect to a redis instance listening on a unix socket in this fashion:

var redis = require("redis"),
     redisClient = redis.createClient("/tmp/redisTest.sock");

as well as being able to connect to redis when passing in the cnxOptions directly as:

var config = {
   port: 6379, 
   host: '127.0.0.1',
   options: {}
};

var redis = require("redis"),
     redisClient = redis.createClient(config);

my pull request attempts to check if you are sending a unix path or connection options in port_arg and set the cnxOptions correctly to net.createConnection

this should fix some, if not all of the connection regressions described in #632

[brycebaril]

Thanks for the submission -- went with PR #642 which had a more complete implementation. It's pushed as 0.12.0