Job manager
 A simple set of classes to manage jobs, and their dependencies. The basic functionality is to:
 * record jobs to be performed
 * record dependencies between jobs (should be a DAG, but that's not envorced)
 * get a list of current jobs which are ready to be started (those that don't have dependent jobs which are not yet done)
 * check if a single job can start
 * get aggregate counts of unmet dependencies
 * get list of dependencies
Merge pull request #404 from aabes/pull-req-master-1385f2a8a909ad89e77e3fece420274e3b76dc89

Add job manager in support of orchastrating things in jig [1/1]