Move ApplicationContextTestUtils to src/test

Move ApplicationContextTestUtils from src/main to src/test since it
is probably of limited use to others.

Fixes gh-1034

spring-boot/src/test/java/org/springframework/boot/builder/SpringApplicationBuilderTests.java

@@ -22,7 +22,6 @@ import java.util.Collections;
 
 import org.junit.After;
 import org.junit.Test;
-
 import org.springframework.boot.test.ApplicationContextTestUtils;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;

spring-boot/src/test/java/org/springframework/boot/test/ApplicationContextTestUtils.java

@@ -16,21 +16,18 @@
 
 package org.springframework.boot.test;
 
-
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ConfigurableApplicationContext;
 
 /**
- * Application context related test utilities.
+ * Internal application context related test utilities.
  * 
  * @author Stephane Nicoll
- * @since 1.1.1
  */
 public abstract class ApplicationContextTestUtils {
 
 	/**
-	 * Closes this {@link ApplicationContext} and its parent hierarchy
+	 * Closes this {@link ApplicationContext} and its parent hierarchy if any.
-	 * if any.
 	 * @param context the context to close (can be {@code null})
 	 */
 	public static void closeAll(ApplicationContext context) {

spring-boot/src/test/java/org/springframework/boot/test/ApplicationContextTestUtilsTests.java

@@ -16,15 +16,16 @@
 
 package org.springframework.boot.test;
 
-import static org.mockito.BDDMockito.given;
-import static org.mockito.Mockito.*;
-
 import org.junit.Test;
-
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ConfigurableApplicationContext;
 
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
 /**
+ * Tests for {@link ApplicationContextTestUtils}.
  * 
  * @author Stephane Nicoll
  */
@@ -47,7 +48,6 @@ public class ApplicationContextTestUtilsTests {
 		ConfigurableApplicationContext parent = mock(ConfigurableApplicationContext.class);
 		given(mock.getParent()).willReturn(parent);
 		given(parent.getParent()).willReturn(null);
-
 		ApplicationContextTestUtils.closeAll(mock);
 		verify(mock).getParent();
 		verify(mock).close();