CompilerAdapter for <javac> task + test for compiler attribute

No test for the typedef <withKotlin/> because Ant 1.7 doesn't seem to support typedef inside <javac>

compiler/integration-tests/testData/javacCompiler/root1/hello.kt

@@ -0,0 +1,7 @@
+package hello
+
+fun main(args : Array<String>) {
+    for (s in arrayList("a"))
+      println("Hello, $s!")
+    j.Java().f();
+}

compiler/integration-tests/testData/javacCompiler/root1/j/Java.java

@@ -0,0 +1,14 @@
+package j;
+
+import java.lang.String;
+import java.lang.System;
+
+public class Java {
+    public void f() {
+        System.out.println("Java");
+    }
+
+    public static void main(String[] args) {
+        hello.HelloPackage.main(new String[] {});
+    }
+}