Dynamic queues

Currently, when new queues are added to Redis, workers listening to all queues ('*') do not see the new queues without a restart. This change will refresh the list of queues when polling for jobs.

Here's a small sample app demonstrating the dynamic fetching of queues.
```csharp
using System;
using System.Threading;
using Newtonsoft.Json.Linq;

namespace ResqueTest
{
    class MyJob : Resque.Jobs.BaseJob
    {
        public override void Perform()
        {
            Console.WriteLine("EXECUTING MyJob");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Resque.Resque.SetRedis();
            Resque.Resque.AddJob("MyJob", typeof(MyJob));

            Resque.Resque.Enqueue("fooqueue", "MyJob", new JObject());
            var worker = new Resque.Worker("*");
            Thread thread = new Thread(() => worker.Work(5));
            thread.Start();

            Thread.Sleep(5000);
            Resque.Resque.Enqueue("barbqueue", "MyJob", new JObject());
            Thread.Sleep(5000);
            worker.Shutdown();
            thread.Join();
            Console.ReadLine();
        }
    }
}
```

Output:

```
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Found job on fooqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Got fooqueue
EXECUTING MyJob
[1/1/0001 12:00:00 AM] Done (Job{fooqueue}|ID: 4ae71336e44bf9bf79d2752e234818a5|MyJob|[{}])
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Found job on barbqueue
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Got barbqueue
EXECUTING MyJob
[1/1/0001 12:00:00 AM] Done (Job{barbqueue}|ID: 4ae71336e44bf9bf79d2752e234818a5|MyJob|[{}])
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Checking barbqueue
[1/1/0001 12:00:00 AM] Checking fooqueue
[1/1/0001 12:00:00 AM] Sleeping for 1000
[1/1/0001 12:00:00 AM] Exiting.
```