jme3-core/src/test: upgrade MockitoJUnitRunner from deprecated version (#1658)

jme3-core/src/test/java/com/jme3/material/MaterialTest.java

@@ -50,7 +50,7 @@ import java.util.EnumSet;
 import static org.junit.Assert.*;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
+import org.mockito.junit.MockitoJUnitRunner;
 
 @RunWith(MockitoJUnitRunner.class)
 public class MaterialTest {

jme3-core/src/test/java/com/jme3/material/plugins/J3MLoaderTest.java

@@ -17,7 +17,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.Mockito;
-import org.mockito.runners.MockitoJUnitRunner;
+import org.mockito.junit.MockitoJUnitRunner;
 
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.verify;

jme3-core/src/test/java/com/jme3/material/plugins/LoadJ3mdTest.java

@@ -42,7 +42,7 @@ import java.util.*;
 import static org.junit.Assert.assertEquals;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
+import org.mockito.junit.MockitoJUnitRunner;
 
 @RunWith(MockitoJUnitRunner.class)
 public class LoadJ3mdTest {