Add back DEFAULT_VERBOSE

This restores the behavior where --verbose to ansible-report controlled
how non-changed tasks were reported.  Until ansible-report better
supports intersection and union on the cli, this will need to stay.
add more logging to manager.py and utils.py
make naive calls if no args supplied to find_*
fix callback plugin to only instantiate self.playbook once
add logging statement to screen plugin
create/drop index for task.changed during migration