Implement PlayerView and PlayerStrategy
Add toString for Card.
Add ControllerTest.
Merge remote-tracking branch 'origin/experimental'

Conflicts:
	src/main/java/coward/big2/Card.java
	src/test/java/coward/big2/ControllerTest.java
Correct PlayerStrategy to use ImmutableSet<Card> instead of Set<Card>
since Controller.playCards() expects an immutable set of cards.
Fix SimplePlayerStrategy and add dummy methods in Controller.