Fix bug where worker died from monitoring views.

Fixes #288.

Conflicts:
	rq/worker.py
Python 2.6 fix.
Bump version to 0.3.12.

Conflicts:
	CHANGES.md
Merge branch 'hotfix-0.3.12'

Conflicts:
	CHANGES.md
	rq/worker.py
Fix NameError.

This was the result of a faulty merge. I'm sorry.
Bump version to 0.3.13.
Merge branch 'hotfix-0.3.13'

Conflicts:
	CHANGES.md