Added tests for thread-pool pattern

Fixed concurrency problem in id generation of Task

thread-pool/src/test/java/com/iluwatar/threadpool/PotatoPeelingTaskTest.java

@@ -0,0 +1,17 @@
+package com.iluwatar.threadpool;
+
+/**
+ * Date: 12/30/15 - 18:23 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class PotatoPeelingTaskTest extends TaskTest<PotatoPeelingTask> {
+
+  /**
+   * Create a new test instance
+   */
+  public PotatoPeelingTaskTest() {
+    super(PotatoPeelingTask::new, 200);
+  }
+
+}