Back-marge master into scheduler-integration.
Merge @selwin's WIP on integration.
Fail hard when the 'data' key does not exist.
If there is no 'data' field, this cannot be a valid Job.
Whoops.
Set result_ttl of periodic jobs to 0 by default.

This means results are deleted immediately for periodic jobs, unless
a value is explicitly provided.  I think this is a saner default,
because using the scheduler out of the box means Redis slowly fills up
with job results (possibly empty).
Don't set the result_ttl to anything special.

This keeps things consistent with the default `result_ttl` behaviour
when enqueueing (non-periodic) jobs.  There's no need to treat these
differently.
Allow rqworker to run more silently.
Prepare for next 0.3.x version.
Remove .env.fish.
Merge branch 'master' into scheduler-integration
Merge branch 'scheduler-integration' of git://github.com/nvie/rq into scheduler-integration