v1.8.0: Added ability to automatically retry jobs that threw errors

Remove console.logs

v1.7.1: Added payload data when emitting the reserved jobs event

Merge pull request #2 from drey101/master

Default message for error encountered while establishing error is mod…

Add more data to error

Merge pull request #1 from drey101/master

When handler encounters an error, make it emit an error

v1.6.0: Events: enable class names and return jobdata

If the handler is an ES6 Class, return `handler.constructor.name` instead of `handler.type` in events.
In the `job.handled` event, return the jobdata as the second parameter.