Add top-level python directory to opensource repo

This adds a home in our opensource repo for python libraries and binaries,
under a top-level "python" directory.  Future CLs will relocate ICANN
reporting bits and pieces to new homes under this directory, and will use
the MOE configuration and python_directory_import rule defined here.

This approach is roughly modeled on the protobuf Bazel opensource project,
which also uses a top-level directory for various languages, and also uses
the "imports" parameter to exclude that directory in python module names:
  https://github.com/google/protobuf/blob/v3.0.0-beta-3/BUILD#L568
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=127459882

javatests/google/registry/xml/XmlTestUtilsTest.java

@@ -0,0 +1,60 @@
+// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.xml;
+
+import static google.registry.util.ResourceUtils.readResourceUtf8;
+import static google.registry.xml.XmlTestUtils.assertXmlEquals;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link XmlTestUtils}. */
+@RunWith(JUnit4.class)
+public class XmlTestUtilsTest {
+
+  @Rule
+  public final ExpectedException thrown = ExpectedException.none();
+
+  void runTest(String file1, String file2) throws Exception {
+    String s1 = readResourceUtf8(getClass(), "testdata/" + file1);
+    String s2 = readResourceUtf8(getClass(), "testdata/" + file2);
+    assertXmlEquals(s1, s2);
+  }
+
+  @Test
+  public void testSelfEquality() throws Exception {
+    runTest("simple.xml", "simple.xml");
+  }
+
+  @Test
+  public void testInequality() throws Exception {
+    thrown.expect(AssertionError.class);
+    runTest("simple.xml", "twoextensions_feeThenLaunch.xml");
+  }
+  
+  @Test
+  public void testMultipleElementsInDifferentNamespaces() throws Exception {
+    runTest("twoextensions_feeThenLaunch.xml", "twoextensions_launchThenFee.xml");
+  }
+  
+  @Test
+  public void testMultipleElementsInDifferentNamespaces_differentValues() throws Exception {
+    thrown.expect(AssertionError.class);
+    runTest("twoextensions_feeThenLaunch.xml", "twoextensions_feeThenLaunch2.xml");
+  }
+}