Fix an autoloading issues from duplicate constants.

The module called Source was not loading, the actual Source class was.
Fix jobs not getting assignment ID.

Blame my inability to read the resque_spec README, and its really weird
example cases that make it hard to understand.
Cleanup, real dummy time job.
Add an integration test for the jobs and data binding.

And it all comes together, for reals.
Convenience methods in jobs to fetch attributes.
Update assignments as data changes.

Not nearly as awful as I was expecting.  The updates aren't efficient
yet, but I'll fix that.