Add providers for controlling state of a light.
These are needed to allow development while not running on raspi.
Refactoring of build-status related logic.
New behavior uses separate light-managers (i.e. building, pass/fail, etc.).
Each manager has a set of configs. for controlling its pin-interaction and what provider to use.
Update README to reflect new environment variables needed.
Merge pull request #8 from williambogaiv/master

Refactor main app. logic to use new light managers and providers