Began on tests for Race class.

- Made really good progress using Mockito and calling .handle() on animation timers

#story[881]

mock/src/main/java/seng302/Model/Race.java

@@ -54,7 +54,7 @@ public class Race implements Runnable {
      * Countdown timer until race starts.
      */
 
-    private AnimationTimer countdownTimer = new AnimationTimer() {
+    protected AnimationTimer countdownTimer = new AnimationTimer() {
         long currentTime = System.currentTimeMillis();
         long timeLeft;
         @Override