added missing @Override

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@776409 13f79535-47bb-0310-9956-ffa450edef68

src/test/org/apache/commons/math/stat/ranking/NaturalRankingTest.java

@@ -30,10 +30,12 @@ public class NaturalRankingTest extends TestCase {
         super(arg0);
     }
 
+    @Override
     protected void setUp() throws Exception {
         super.setUp();
     }
 
+    @Override
     protected void tearDown() throws Exception {
         super.tearDown();
     }