remove unused _locales/ (i18n)

Author: 0xdevalias

_locales/en/messages.json

@@ -5,7 +5,6 @@
   "name": "New Window With Tabs To Right",
   "description": "This extension creates a new window with the tabs to the right of the currently selected tab.",
   "homepage_url": "http://devalias.net/dev/chrome-extensions/",
-  "default_locale": "en",
   "icons": {
     "16": "icons/NewWindowWithTabsToRight-Icon@16px.png",
     "32": "icons/NewWindowWithTabsToRight-Icon@32px.png",