HTML-776 Add an optional date attribute to latestObs, earliestObs, latestEncounter and currentProgramWorkflowStatus to limit the date search for each of the expressions (#241)
* HTML-776 add a latest date cut off for latestObs, latestEncounter and currentWorkflowStatus velocity expressions
* Do not catch the exception in allObs so that it bubbles up to the caller
* Handle date parsing exceptions and clean up methods to reduce redirection