Convert to using logging instead of bare file writes in TaskRegistry

[nickrsan]

We should log using the logging package. This needs some planning, but I think each instance of the main classes should instantiate its own logger as, e.g. self.log and then it closes that out before deletion. This would also significantly improve logging in the application over printing

[nickrsan]

Adam, FYI, I'm tentatively assigning this one to you - it's not urgent, but just putting it on your eventual list