Make sure translation tools are lint checked

They do not have a .js suffix so eslint isn't finding them
automatically.

package.json

@@ -19,7 +19,7 @@
     "vendor/pako"
   ],
   "scripts": {
-    "lint": "eslint app core po tests utils",
+    "lint": "eslint app core po/po2js po/xgettext-html tests utils",
     "test": "karma start karma.conf.js",
     "prepublish": "node ./utils/use_require.js --as commonjs --clean"
   },

po/.eslintrc

@@ -0,0 +1,5 @@
+{
+    "env": {
+        "node": true,
+    },
+}