Find areas in code base that could use more logging statements

This is the second pass in editing the Designate logging statements. The first pass can be found at https://blueprints.launchpad.net/designate/+spec/standardize-logging .

This pass will seek new places in the Designate code base where logging statements would potentially be useful. This will require studying Designate for existing patterns in the placement of log statements, collaboration with the Designate community for suggestions, etc., in addition to the changes themselves.