make jnuit5 tests actually executable in gradle

build.gradle

@@ -48,6 +48,12 @@ subprojects {
 	// dependencies that all sub-projects have 
 	dependencies {
 		testCompile 'org.junit.jupiter:junit-jupiter-api:5.2.0'
+    	testRuntime 'org.junit.jupiter:junit-jupiter-engine:5.2.0'
+    	testRuntime 'org.junit.platform:junit-platform-launcher:1.2.0' // needed by eclipse
+	}
+	
+	test {
+	    useJUnitPlatform()
 	}
 }