Update Phabricator to work with more modular translations

Summary:
Ref T7152. Ref T1139. This updates Phabricator so third-party libraries can translate their own stuff. Also:

  - Hide "All Caps" when not in development mode, since some users have found this a little confusing.
  - With other changes, adds a "Raw Strings" mode (development mode only).
  - Add an example silly translation to make sure the serious business flag works.
  - Add a basic British English translation.
  - Simplify handling of translation overrides.

Test Plan:
  - Flipped serious business / development on and off and saw silly/development translations drop off.
  - Switched to "All Caps" and saw all caps.
  - Switched to Very English, Wow!
  - Switched to British english and saw "colour".

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7152, T1139

Differential Revision: https://secure.phabricator.com/D11747

src/applications/base/controller/PhabricatorController.php

@@ -96,13 +96,9 @@ abstract class PhabricatorController extends AphrontController {
       $request->setUser($user);
     }
 
-    $translation = $user->getTranslation();
-    if ($translation &&
-        $translation != PhabricatorEnv::getEnvConfig('translation.provider')) {
-      $translation = newv($translation, array());
-      PhutilTranslator::getInstance()
-        ->setLanguage($translation->getLanguage())
-        ->addTranslations($translation->getCleanTranslations());
+    $locale_code = $user->getTranslation();
+    if ($locale_code) {
+      PhabricatorEnv::setLocaleCode($locale_code);
     }
 
     $preferences = $user->loadPreferences();