Add support for manhole to tracker.py
Merge pull request #344 from whirm/tracker_manhole

Add support for manhole to tracker.py
Fix test_candidates.py
DROPME debug
DROPME debug
Refactor start_walking to unwind the call stack a bit.
Do not immediately call the periodic cleanup function to avoid recursion.
Refactor the requestcache to extend TaskManager
Remove the delayed call when timing out.