Add Junit tests

[bronhuston]

Add additional Junit tests to the existing test cases.

~estimated 100

[pconrad]

@sarahdarwiche with @benjaminhartl

[kjorg50]

Since the interactions of the GUI components are the main feature of the game, you should also explore how to write JUnit tests for GUIs. Using the Java Robot class should be helpful. Here is one link to get started looking for more info

http://docs.oracle.com/javase/7/docs/api/java/awt/Robot.html

That way, you could things like making sure the ball hits off of the paddles and walls correctly

[zhanchengqian]

F16 OK

[brianslee]

Additional tests would be good. W18 Ok 100 Pts.

[brianslee]

Implemented in w18 branch. Transfer code over to main branch.