Add to_s
Make status timing an object attribute
Clean up status logic
Make status timing an object attribute (part 2)
Refactor child processes collection

Instead of relying on trapping SIGCHLD, we'll explicitly look for dead children whenever we're waiting for something to happen.
Make 'children' hash an instance attribute
Pop out run queue data in dry-run
Testing comment update
Comment and whitespace cleanup
Use Open4::popen4 to wrap knife command