Fix constant spelling mistake.
Fix persistent ID socket bug

Using persistent socket IDs doesn't allow for reconnects.
Remove zmqid flag
Fix error with no config flags.
Move startup routines out of class.

Cannot unit test server when startup routines are part of class
definition.
Add unit test for server.
Fix worker reconnect handling.

Instead of forgetting active workers, keep track of them and purge
them if they don't respond in the maximum heartbeat time.

This change requires workers to heartbeat if their job will take
longer than the maximum configured heartbeat interval.