The Slave class forks a process and starts a drb server in the child using any
object as the server. the process is detached so it is not required (nor
possible) to wait on the child pid. a Heartbeat is set up between the parent
and child processes so that the child will exit of the parent exits for any
reason - preventing orphaned slaves from running indefinitely. the purpose of
Slaves is to be able to easily set up a collection of objects communicating via
drb protocols instead of having to use IPC.

Authors:
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Ara T. Howard