feature adds:
 * add convenience_config_vars which can be a list files containing key = value to be substituted in workflows.  e.g. 1: mysql -u %%(some.db.host)s -p %%(some.db.pass)s.  configurable at both service (all workflows) or individual workflow levels
 * add ability to pass additional environment variables to remote execution.
 * both new features configurable- see WF-template.ini for directives