First stab at writing implementing job dependency.
Don't enqueue waitlisted jobs on failed execution.
Avoid race conditions when enqueueing job with dependency.
Simplify enqueue_waitlist by using lpop.
Internally renamed the term "parent" to "dependency".
Merge branch 'master' of git://github.com/nvie/rq into job_dependency

Conflicts:
	rq/queue.py
Don't fail if job dependency is modified during enqueue process.
Writes an optional specified PID file on startup
take REDIS_URL from settings if exists
Removed alternative parameters for PID file creation
Polished help message for PID file specification
Merge remote branch 'original/master'
deprecate use of host/db/port options for Redis
Merge pull request #214 from Plexical/write-pid-file

Writes an optional specified PID file on startup
Release 0.3.8.
register_sentry breaks failed queue when func cannot be imported
Fixes an issue where register_sentry breaks when logging jobs with
unimportable function.
Merge pull request #238 from selwin/logging-import-errors

register_sentry fixes
run tests on py33
changes by python-modernize