Implementation of tags to jobs

Created by: saromanov

Hi, guys! I implemented tags for jobs, and its looks something like:

var videoQueue = Queue('video transcoding', 6379, '127.0.0.1');
videoQueue.process(function(job, done){
  videoQueue.getByTag('active', 'bar').then(function(jobs){
        console.log("Active jobs: ", jobs);
    })

  job.progress(42);
  done();
});
videoQueue.add({video: 'http://example.com/video1.mov'}, {tags:['bar']});
videoQueue.add({video: 'http://example.com/video2.mov'});
videoQueue.add({video: 'http://example.com/video3.mov'}, {tags:['foo','bar']});
videoQueue.add({video: 'http://example.com/video4.mov'}, {tags:['foo']});

Where, signature of getByTag is getByTag(type of jobs ['active','delayed',..], tag)

In general, we can group some of jobs by tag, get it during the work of queue on some of state(progress, paused, failed...) and process it. What do you think about this?