Allowed settings to override hardcoded vars...

Logical change to allow options to override two variables;
- Boolean to decide if late jobs are run
- The definition (interval) of a late job

Usage:
```
    var recurringJobId = pomelo.scheduleJob(rule, job, data, {
        runLateJobs: false,
        lateJobInterval: 5000
    });
```

Propose you merge this but don't document it as here may be more use cases for settings that I may find over the next few weeks as I integrate this module.

Great work, thankyou!!