Merge pull request #381 from superklamer/FlattenerTest

#379 flatten-array: add @Ignore to tests

exercises/flatten-array/src/test/java/FlattenerTest.java

 import org.junit.Before;
 import org.junit.Test;
+import org.junit.Ignore;
 
 import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
               8)));
     }
 
+    @Ignore
     @Test
     public void testFiveLevelsOfNestingWithNoNulls() {
         assertEquals(
               "-2")));
     }
 
+    @Ignore
     @Test
     public void testSixLevelsOfNestingWithNoNulls() {
         assertEquals(
               "8")));
     }
 
+    @Ignore
     @Test
     public void testSixLevelsOfNestingWithNulls() {
         assertEquals(
               "negative two")));
     }
 
+    @Ignore
     @Test
     public void testNestedListsFullOfNullsOnly() {
         assertEquals(