Updated queue, scheduler and worker to pass back error on connection fai...

At the moment, if you do:

``` js
var connectionDetails = {
  host:      "127.0.0.1",
  password:  "",
  port:      "wrongport",
  database:  0,
}
var queue = new NR.queue(
  { connection: connectionDetails },
  jobs,
  function(err) {
    if(err) { throw err; }  // Never thrown because err is always undefined
    console.log('Task Queue started OK');
  }
);
```

The error handling won't kick in because the connection error is never passed through.

This PR fixes this, and hopefully also for the worker and scheduler.

**Note:** I couldn't get the scheduler tests to work correctly with the extra test I added, so I had to `xit` it out. Please could you take a look and see what is going wrong (try un-xitting and see what I mean).

Oh, and I added a few missing semicolons just for good measure :-)