Graceful shutdown of workers on exq terminate

[akira]

Have manager shutdown workers and wait for a timeout when a terminate is sent to it. This depends on #5 having a worker pool for workers.

[j-mcnally]

would this give workers a chance to cleanup if Manager terminates / application recieves SIGKILL/SIGTERM ?

[akira]

I wasn't thinking of SIGKILL/SIGTERM, I was specifically thinking of calling terminate on the Manager process, which would then terminate it's children with a timeout. Not sure how Erlang handles signals, for that would have to do some research.

[akira]

I had some ideas on the process model for this, need to try it out when I get the chance. Was thinking of looking into an existing worker pool library (like pool_boy, epocxy, or worker_pool) to see if that will help us out any.

[akira]

Implemented by #147