job.cancel should remove references from related Queue/Scheduler.
Added a Registry class to store a map of functions to jobs that can be
used to cheaply determine whether a callable is scheduled or queued.
Job should first be deleted before removed from Queue/scheduler.
Refactor "scheduler.enqueue_in" and "scheduler.enqueue_at" to use
"scheduler.schedule".
Merge branch 'master' of git://github.com/nvie/rq into scheduler-integration

Conflicts:
	rq/queue.py
Merge branch 'scheduler-integration' of git://github.com/nvie/rq into scheduler-integration
Use pipeline when canceling jobs.
Call the safe method _pipeline() instead.

This is related to supporting both Redis and StrictRedis connections
since 0.3.5. See commit 54254f227112f6cd32cc47ee1a2494ef9923a10e for
more details.
Fix whitespace.
Don't pollute the default DB with our test data.
Merge branch 'selwin-scheduler-integration' into scheduler-integration