Add a retry option

Hi @didil,

So I consolidated my previous attempt (#3) to one option:

```-retry false``` or ```-r false``` - Tells Sidekiq to not retry the job, if the job fails
```-retry 5``` or ```-r 5``` - Tells Sidekiq to retry the job at most 5 times, if the job fails

This now mimics the options of sidekiq's advanced options (https://github.com/mperham/sidekiq/wiki/Advanced-Options#workers)