The Scheduler is responsible for monitoring the schedule and retry queues. These queues use a Redis sorted set (term?) to schedule and pick off due jobs. Once a job is at or past it's execution date, the Scheduler moves the job into the live execution queue.

Runs on a timed loop according to scheduler_poll_timeout.

Initialization:

• :name - Name of target registered process
• :namespace - Redis namespace to store all data under. Defaults to "exq".
• :queues - Array of currently active queues (TODO: Remove, I suspect it's not needed).
• :redis - pid of Redis process.
• :scheduler_poll_timeout - How often to poll Redis for scheduled / retry jobs.