Various reworkings.

Add a function to release/unclaim a job on the claimer object and
expose that functionality in the job object. Add an await() method
on the job which will do basic spinning (later functionality can
do more advanced types of waiting). Add a useful str() function to
the job so that it can be easily printed with some useful info about
it.
Remove impl of erasing which doesn't do much and allow for job reposting.
Add a more useful name that shows this is a task.
Adjust some of the states jobs and workflows could be in.
Add a nicer string name that shows what the class name is.
After adding reposting/unclaiming reflect those changes here.
Add a thread posting/claiming example and rework tests to use it.
Merge pull request #11 from harlowja/new-hotness

New hotness