Include test that requires JDK 9

Author: pvorb

spring-boot-samples/spring-boot-sample-tomcat-http2/src/test/java/sample/tomcat/http2/SampleTomcatHttp2ApplicationTests.java

@@ -33,7 +33,6 @@
 import okhttp3.Request;
 import okhttp3.Response;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -87,7 +86,6 @@ public void testHttp11() throws Exception {
 	 * This only works when both tomcat-native is in PATH <em>and</em> it is running on
 	 * Java 9, since OkHttp makes use of Java 9's support for ALPN.
 	 */
-	@Ignore
 	@Test
 	public void testHttp2() throws Exception {
 		final Request request = new Request.Builder()