Fix VelocityProperties and Annotation Processor Logging

Created by: dbluhm

This PR fixes two issues:

• VelocityProperties was set to load from a file when it should have been loading from a resource
• Annotation processor logging the way I set it up would conflict with any logger implementations put on dependent projects. I reverted the main DataElementProcessor to extend the usual AbstractProcessor and wrote a quick wrapper around it for use in testing that adds in the logging functionality. With that in place, the annotation-processor-logging library is a test only dependency, solving our logger conflict problems.