DDF-487: Add created date and modified date filter support for catalog:dump

Also adds some tests for the original functionality.
Just a personal preference, but I have been trying to not put TODOs in code, but instead make a ticket with the information in that ticket. Makes it a little more likely that it won't get forgotten about. I know you've already made the ticket (https://tools.codice.org/jira/browse/DDF-535), but I just wanted to make the note for reference.