Begin moving Phabricator configuration into PHP

Summary: Ref T2255. Ref T2221. Lay the groundwork to move configuration into PHP, so we can show descriptions in the web UI, do typechecking, disable application options when an application is uninstalled, etc.

Test Plan:
{F28421}
{F28420}
{F28422}

Reviewers: codeblock, btrahan, vrana

Reviewed By: codeblock

CC: aran

Maniphest Tasks: T2221, T2255

Differential Revision: https://secure.phabricator.com/D4306

src/applications/config/controller/PhabricatorConfigGroupController.php

@@ -0,0 +1,68 @@
+<?php
+
+final class PhabricatorConfigGroupController
+  extends PhabricatorConfigController {
+
+  private $groupKey;
+
+  public function willProcessRequest(array $data) {
+    $this->groupKey = $data['key'];
+  }
+
+  public function processRequest() {
+    $request = $this->getRequest();
+    $user = $request->getUser();
+
+    $groups = PhabricatorApplicationConfigOptions::loadAll();
+    $options = idx($groups, $this->groupKey);
+    if (!$options) {
+      return new Aphront404Response();
+    }
+
+    $title = pht('%s Configuration', $options->getName());
+
+    $header = id(new PhabricatorHeaderView())
+      ->setHeader($title);
+
+    $list = $this->buildOptionList($options->getOptions());
+
+    $crumbs = $this
+      ->buildApplicationCrumbs()
+      ->addCrumb(
+        id(new PhabricatorCrumbView())
+          ->setName(pht('Config'))
+          ->setHref($this->getApplicationURI()))
+      ->addCrumb(
+        id(new PhabricatorCrumbView())
+          ->setName($options->getName())
+          ->setHref($this->getApplicationURI()));
+
+    return $this->buildApplicationPage(
+      array(
+        $crumbs,
+        $header,
+        $list,
+      ),
+      array(
+        'title' => $title,
+        'device' => true,
+      )
+    );
+  }
+
+  private function buildOptionList(array $options) {
+    assert_instances_of($options, 'PhabricatorConfigOption');
+
+    $list = new PhabricatorObjectItemListView();
+    foreach ($options as $option) {
+      $item = id(new PhabricatorObjectItemView())
+        ->setHeader($option->getKey())
+        ->setHref('/config/edit/'.$option->getKey().'/')
+        ->addAttribute(phutil_escape_html($option->getSummary()));
+      $list->addItem($item);
+    }
+
+    return $list;
+  }
+
+}