Scenario folder name should not be hard-coded in Coordinator constructor

[jdalbey]

Currently the Scenario folder name is hard-coded in the path to the Cardfile.xml that the Coordinator loads for the CAD clients.    It would be better placed in a config file, in the manner of SCENARIOS_DIR property of simulation manager.   

However, it doesn't seem consistent to have the Coordinator refer to the Sim Mgr to get a property that really belongs to CAD clients.  So maybe this property should be moved out of Sim Mgr to CAD Server properties?  I'm uncertain what the best tactic is here, so I'm just leaving this ticket to be resolved in the future.