Put Parrot in its own process group so calls to tcsetpgrp succeed in signal
handling (and so SIGTTOU and SIGTTIN are not sent to other processes in
Parrot's process group).

Fixes #44.
This should be the process group not pid.
1. Added long options to sge_submit_workers to match those in the work_queue_worker.
2. Updated the man page and the help message to reflect the changes.

Similar to changes made to the condor_submit_workers recently:
1. the -c option (added for the --cores options) was removed;
2. long options using equal signs won't work in sge_submit_workers either, e.g.: '--timeout=30'. A valid one would be: '--timeout 30'
Merge pull request #115 from batrick/master

Put parrot in its own process group.  Fixes #44
Minor documentation fix for WQ Python API
Simplify the code for handling unresponsive workers.
1. Use keepalives to find and remove connected but unresponsive workers
in any state (init/ready/busy/full).
2. Use the last time a message was received from the worker to space out
the sending of keepalive checks.
3. Change keepalive_timeout and keepalive_interval to integers.