v0.0.4

• Keep track of running idempotent jobs
• Add job_failed and job_schedule_retry signals
• Add Sentry integration
• Arguments passed to signal handlers are not copied anymore
• Rename Spinach class to Engine
• Allow to retry jobs with RetryException
• Make Spinach more reliable to connection errors
• Handle receiving unknown tasks
• Allow to schedule jobs in batch
• Allow to define tasks in the Engine directly