add configuration file support

* Add work_queue specific configuration options
* Global options added for Yerba

	modified:   bin/yerbad
	modified:   yerba.cfg.example
	modified:   yerba/workqueue.py
	modified:   yerba/yerba.py
add ubuntu upstart job to scripts

* Upstart job daemon script created for running on an Ubuntu Server.

	new file:   scripts/catalog_server.conf
	new file:   scripts/work_queue_pool.conf
	new file:   scripts/yerba.conf
add barebones health check route
fixed running and failed status

	modified:   yerba/workflow.py
increase count on a poll attempt

	modified:   bin/yerba
check that the argument is a valid path

	modified:   yerba/workflow.py