Several new features for OSX version:

- Use Notifications for a more robust way to tell which app is active
- Record window titles for active app
- Record URL of active tab if active app is Chrome
- Record screen sleep events
remove unused imports and turn off debug printing
Add a .app version for OSX
Change dev flag to false on
Merge pull request #5 from jcjohnson/master

Enhancements for OSX version