Convert AppEngineConnection to use HttpTransport

Make AppEngineConnection use HttpTransport through HttpRequestFactory and
create factory factories for localhost and HTTPOverRPC.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143680257

java/google/registry/tools/LocalhostRequestFactoryComponent.java

@@ -0,0 +1,46 @@
+// Copyright 2016 The Nomulus 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.tools;
+
+import com.google.api.client.http.HttpRequest;
+import com.google.api.client.http.HttpRequestFactory;
+import com.google.api.client.http.HttpRequestInitializer;
+import com.google.api.client.http.javanet.NetHttpTransport;
+
+/**
+ * Request factory for dealing with a "localhost" connection.
+ *
+ * <p>Localhost connections go to the App Engine dev server. The dev server differs from most HTTP
+ * connections in that they don't require OAuth2 credentials, but instead require a special cookie.
+ *
+ * <p>This is an immplementation of HttpRequestFactoryComponent which can be a component dependency
+ * in a Dagger graph used for providing a request factory.
+ */
+class LocalhostRequestFactoryComponent implements HttpRequestFactoryComponent {
+  @Override
+  public HttpRequestFactory httpRequestFactory() {
+    return new NetHttpTransport()
+        .createRequestFactory(
+            new HttpRequestInitializer() {
+              @Override
+              public void initialize(HttpRequest request) {
+                request
+                    .getHeaders()
+                    .setCookie("dev_appserver_login=test@example.com:true:1858047912411");
+              }
+            });
+  }
+}
+