Add a retry option

[codebender]

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)

[coveralls]

Coverage remained the same when pulling ba5f6d0 on MisterBender:feature/add_retry_arg into 01b343c on didil:master.

[didil]

Thanks but we've had to modify the way the default options are handled due to a breaking change in sidekiq 2.15.0 so that conflicts with your pull request, please have a look at the current master, pull it, make the changes and send a new pull request, it should be quick