Move files in Phabricator one level up

Summary:
- `kill_init.php` said "Moving 1000 files" - I hope that this is not some limit in `FileFinder`.
- [src/infrastructure/celerity] `git mv utils.php map.php; git mv api/utils.php api.php`
- Comment `phutil_libraries` in `.arcconfig` and run `arc liberate`.

NOTE: `arc diff` timed out so I'm pushing it without review.

Test Plan:
/D1234
Browsed around, especially in `applications/repository/worker/commitchangeparser` and `applications/` in general.

Auditors: epriestley

Maniphest Tasks: T1103

src/aphront/response/AphrontJSONResponse.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * 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.
+ */
+
+/**
+ * @group aphront
+ */
+final class AphrontJSONResponse extends AphrontResponse {
+
+  private $content;
+
+  public function setContent($content) {
+    $this->content = $content;
+    return $this;
+  }
+
+  public function buildResponseString() {
+    $response = $this->encodeJSONForHTTPResponse($this->content);
+    return $this->addJSONShield($response, $use_javelin_shield = false);
+  }
+
+  public function getHeaders() {
+    $headers = array(
+      array('Content-Type', 'application/json'),
+    );
+    $headers = array_merge(parent::getHeaders(), $headers);
+    return $headers;
+  }
+
+}