XD-500 In cases where a trigger does not exist upon Job Deployment, the Rest Interface needs to hand back a 404 exception vs. a 500 exception.  Also added constants for string values.
As a second note I thinned out the exception stack that is returned is more concise.

Per Code Review reduced the accessiblity the parser and messageSender of parent class.

XD-500 Return a 400 error instead of 404 if the named trigger associated with this job has not been created.

This is per Eric's update to the story.
* Updated code based on code review requests.
** Built error messages using String.format
** Used enum instead of String constants.

XD-500 Merge Conflict Resolved.

We reduced the visibility of this parser and messagesender so that only the abstract deployer can issue commands as a proxy.