Provide a configurable timeout for reaping fanout children

[eric]

I am looking to create a fanout child for each worker that I have and they do not have a unique identifier that persists across worker restart. I was hoping to use hostname:pid as a unique child queue name but need some way to clean up old child queues that are not properly deleted.

@evan suggested on twitter that providing a timeout for reaping the children of a fanout queue would be a good solution to this problem and I completely agree.

[robey]

related feature request from john k:

"An ephemeral fanout queue that streams to you. Open a socket and messages. Close the socket, and, like Markinson, you were never there. There is no Markinson."

sounds similar enough to be part of the same feature. (a markinson child queue would just be a child queue with a destruction timeout of zero.)

[eric]

Looks like this was solved by #87 and #64. Sweet.