Merge branch 'master' into development
Major restructure to chicken object.

Pulled common function of “chicken” out, created a hen object and a
pullet object. Added these to the game. Pullets now eat & drink while
they wait.
Use a Hen instead of a Chicken.
Wire up the Hen to the game.
Wire up pullet logic to the game play.
Add pullet images
Add pullet logic.
Remove pullet game stats.
Clean up pullet images.
Update README
Merge branch 'development'