store multiple instances of jobs in jobs id map to emit events for all

[mojojoji]

Fixes issue #749

[behrad]

Thank you @jojihere
Have you checked if Job.get reaches events.add so that fetched jobs gets into events list?

[mojojoji]

events.add() is not getting called on Job.get(). I have found a subscribe function that does this.
This following merge added that Allow job to be subscribed for event mapping #139
But that only fires for the first job instance created and subscribed as the jobs are stored in a map with key as job id and value the instance of job. I have changed this to key as job id and value as array of job instances. And emit is called for all the instances in this map

[behrad]

I'm ready to merge this, Can you add related test so that I merge?