Moved i18n translations into JSON files

refs https://github.com/TryGhost/Ghost/issues/15502

- plain JSON files are cleaner and less overwhelming than boilerplate JS
  files, and given they're going to be automatically generated, we
  probably won't be able to support comments anyway

ghost/i18n/lib/i18n.js

@@ -14,8 +14,12 @@ module.exports = (lng = 'en') => {
         fallbackLng: false,
 
         resources: {
-            en: require('../locales/en.js'),
-            nl: require('../locales/nl.js')
+            en: {
+                translation: require('../locales/en.json')
+            },
+            nl: {
+                translation: require('../locales/nl.json')
+            }
         }
     });
 

ghost/i18n/locales/en.js

@@ -1,6 +0,0 @@
-// Note: we probably don't need anything in here because we don't expect
-// to translate English to English, but it's here for completeness
-module.exports = {
-    translation: {
-    }
-};

ghost/i18n/locales/en.json

@@ -0,0 +1 @@
+{}

ghost/i18n/locales/nl.js

@@ -1,5 +0,0 @@
-module.exports = {
-    translation: {
-        'Hello': 'Hallo'
-    }
-};

ghost/i18n/locales/nl.json

@@ -0,0 +1,3 @@
+{
+    "Hello": "Hallo"
+}