Allow any file suffix for heap dumps in all JUnit tests

This commit sets the system property
'jdk.management.heapdump.allowAnyFileSuffix' during test execution of
all tests.

Since JDK 8u141 heap dump names are required to have the suffix
'hprof'.

See Bug 535730 to fix the issue and track this workaround.
diff --git a/build.gradle b/build.gradle
index e83c6fa..58a1bc7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -441,6 +441,8 @@
         if (System.properties['ci.build'] == 'true') {
             ignoreFailures = true
         }
+        // Since JDK 8u141 heap dump names are required to have the suffix 'hprof' @see Bug 535730
+        systemProperty "jdk.management.heapdump.allowAnyFileSuffix", "true"
     }
 
     configurations { ecj {} }
diff --git a/medic/org.eclipse.virgo.medic.core/src/test/java/org/eclipse/virgo/medic/dump/impl/HeapDumpContributorTests.java b/medic/org.eclipse.virgo.medic.core/src/test/java/org/eclipse/virgo/medic/dump/impl/HeapDumpContributorTests.java
index 8c7368d..d6a8ad6 100644
--- a/medic/org.eclipse.virgo.medic.core/src/test/java/org/eclipse/virgo/medic/dump/impl/HeapDumpContributorTests.java
+++ b/medic/org.eclipse.virgo.medic.core/src/test/java/org/eclipse/virgo/medic/dump/impl/HeapDumpContributorTests.java
@@ -24,7 +24,6 @@
 import org.eclipse.virgo.medic.dump.DumpContributionFailedException;
 import org.eclipse.virgo.medic.dump.DumpContributor;
 import org.eclipse.virgo.medic.dump.impl.heap.HeapDumpContributor;
-import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
@@ -38,18 +37,13 @@
     @Rule
     public TemporaryFolder dumpDirectory = new TemporaryFolder();
 
-    @Before
-    public void cleanupHeadDumps() {
-        System.setProperty("jdk.management.heapdump.allowAnyFileSuffix", "true");
-    }
-
     @Test
     public void dumpHeap() throws DumpContributionFailedException {
         DumpContributor contributor = new HeapDumpContributor();
 
         String cause = "failure";
         long timestamp = System.currentTimeMillis();
-        Map<String, Object> context = new HashMap<String, Object>();
+        Map<String, Object> context = new HashMap<>();
 
         Dump dump = new StubDump(cause, timestamp, context, new Throwable[0], this.dumpDirectory.getRoot());