add optional 4th param for Redis auth support

[mrtidy]

$ grep ^requirepass /etc/redis/redis.conf 
requirepass booman

For this case, if I only provide Thoonk with hostname and port, then I get an error from RedisClient:

Error Ready check failed: Error: ERR operation not permitted

I verified that existing tests all still pass as well as possible but I haven't committed the modifications of the tests supporting passwords because of a node_redis issue ( redis/node-redis#155 ): test_jobs uses 'ready' and current versions of node_redis fail due to an auth issue.

Thank you.

• jeremiah

[mrtidy]

I just added a second commit to this request. The documentation in README.md is currently wrong. It left off the error parameter in the callback of feed.publish and has the order of the parameters for feed.retract backwards.

current, incorrect docs:

feed.publish('item contents', 'optional id', function(item, id) {
    //done publishing!
});
...
feed.retract('item id', function(id, error) {
    //success?
});

corrected docs:

feed.publish('item contents', 'optional id', function(err, item, id) {
    //done publishing!
});
...
feed.retract('item id', function(err, id) {
    //success?
});

I renamed error in the retract callback to err to be consistent with other docs in this file.

Thank you.

• jeremiah

[mrtidy]

Are there any doubts with this diff? I'm happy to adjust if necessary.

[mrtidy]

It would be helpful if you would merge in this pull.

[mcfazeli]

I also implemented authentication, but on master, I hadn't noticed your pull request before. It's a straightforward change.