Resolve #211, #230: Java8switch

Merge branch 'hbz-java8switch'

Cherry-picked commits from pull request:
 - Make metafcature-core build on Java 8: switch to antlr3.5.2
 - Make travis use the right Java version
 - make the GC wait a little longer in UnitTest for travis...

.travis.yml

@@ -1,6 +1,6 @@
 language: java
 jdk:
-  - openjdk6
+  - oraclejdk8
 
 env:
   global:

pom.xml

@@ -61,7 +61,7 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<targetJdk>1.6</targetJdk>
-		<antlr.version>3.5.1</antlr.version>
+		<antlr.version>3.5.2</antlr.version>
 	</properties>
 
 	<scm>

src/test/java/org/culturegraph/mf/stream/pipe/sort/AbstractTripleSortTest.java

@@ -58,9 +58,11 @@ public void shouldNotFailIfFlushingBeforeFirstRecord() {
 	 * This test case may throw fail unexpectedly as it relies on the
 	 * garbage collector to run when calling {@code System.gc()}. This
 	 * is not guaranteed by the JVM.
+	 *
+	 * @throws InterruptedException
 	 */
 	@Test
-	public void issue192ShouldUnregisterFromTheJVMToNotCauseMemoryLeak() {
+	public void issue192ShouldUnregisterFromTheJVMToNotCauseMemoryLeak() throws InterruptedException {
 
 		// Get weak reference for checking whether the object was actually freed later:
 		final ReferenceQueue<AbstractTripleSort> refQueue = new ReferenceQueue<AbstractTripleSort>();
@@ -71,6 +73,9 @@ public void issue192ShouldUnregisterFromTheJVMToNotCauseMemoryLeak() {
 
 		System.gc();
 
+		// Wait a tiny bit since GC Thread is not immediately done in Java 8
+		Thread.sleep(10);
+
 		assertTrue(weakRef.isEnqueued());
 	}