Added WorkingQueue class.
Implemented WorkingQueue.cleanup().
Moved some logic into worker.prepare_job_execution to make things testable.
Add job to WorkingQueue before execution and remove from WorkingQueue after.
Easy refactoring on decorators.py
Merge pull request #395 from methane/patch-1

Easy refactoring on decorators.py
Add CLI `rq` to empty queues and requeue failed jobs
Merge branch 'master' into cli-rq
Use click.echo instead of print to output
Ignore local.py (it's tested in werkzeug instead).
Show progressbar when requeuing
Make command empty help message friendly
Format empty help message
Add rq command when installing
Add rq info command
Fix import error
Avoid using use_connection, initial queues directly using redis connection
Use -y option to confirm emptying failed queue by default
Use 'with Connection' instead of 'use_connection'
Add testcase for rq_cli