Support reloading/changing of the StateManager with a tronfig.
Add warning to working_dir() context manager.
Merge branch 'release_0.5.2' of github.com:Yelp/Tron into 0.5.2_state_watcher_for_reconfigure
Merge pull request #194 from dnephin/0.5.2_state_watcher_for_reconfigure

0.5.2 state watcher for reconfigure