Enable pygment highlighting for diffusion

Summary:
set the config for the diffusion highlighter. In D202 we
enabled it for differential already.

Test Plan:
opened a python file in diffusion and verified it is highlighted.

Reviewed By: epriestley
Reviewers: epriestley, tuomaspelkonen
CC: aran, epriestley
Differential Revision: 260

src/applications/diffusion/controller/file/DiffusionBrowseFileController.php

@@ -178,6 +178,9 @@ class DiffusionBrowseFileController extends DiffusionController {
         list($text_list, $rev_list, $blame_dict) = $file_query->getBlameData();
 
         $highlightEngine = new PhutilDefaultSyntaxHighlighterEngine();
+        $highlightEngine->setConfig(
+          'pygments.enabled',
+          PhabricatorEnv::getEnvConfig('pygments.enabled'));
 
         $text_list = explode("\n", $highlightEngine->highlightSource($path,
           implode("\n", $text_list)));

src/applications/diffusion/controller/file/__init__.php

@@ -9,6 +9,7 @@
 phutil_require_module('phabricator', 'applications/diffusion/controller/base');
 phutil_require_module('phabricator', 'applications/diffusion/query/filecontent/base');
 phutil_require_module('phabricator', 'infrastructure/celerity/api');
+phutil_require_module('phabricator', 'infrastructure/env');
 phutil_require_module('phabricator', 'infrastructure/javelin/api');
 phutil_require_module('phabricator', 'view/layout/panel');