Update monitor to be an executor listener to better manager active executors
Fix bug where resources added to the registry weren't flagged as visited

Needed to add hashCode and equals to Resource so that any type of hashing data structor (ie, HashMap) could find added Resources.
Added debug and trace loggeing for better trouble-shooting
Add test to verify resource not registered as visited comes up as not-visited
Synchronize the handling of the completed executors

* Synchronize around the active executors data storage
* Add some debug logging
Add a toString impl to the Resource
Populates resources to be type=HTML in all cases
Merge branch 'feature/add-callback-to-executors' into develop