Revert to Babel 5.

packages/xo-server-transport-email/.babelrc

@@ -1,11 +1,12 @@
+
 {
   "comments": false,
   "compact": true,
-  "plugins": [
-    "transform-runtime"
-  ],
-  "presets": [
-    "stage-0",
-    "es2015"
+  "optional": [
+    "es7.asyncFunctions",
+    "es7.decorators",
+    "es7.exportExtensions",
+    "es7.functionBind",
+    "runtime"
   ]
 }

packages/xo-server-transport-email/package.json

@@ -26,18 +26,14 @@
     "dist/"
   ],
   "dependencies": {
-    "babel-runtime": "^6.1.18",
+    "babel-runtime": "^5.8.34",
     "nodemailer": "^1.10.0",
     "nodemailer-markdown": "^1.0.0",
     "pify": "^2.3.0"
   },
   "devDependencies": {
-    "babel-cli": "^6.1.18",
-    "babel-core": "^6.1.21",
+    "babel": "^5.8.34",
     "babel-eslint": "^4.1.5",
-    "babel-plugin-transform-runtime": "^6.1.18",
-    "babel-preset-es2015": "^6.1.18",
-    "babel-preset-stage-0": "^6.1.18",
     "clarify": "^1.0.5",
     "dependency-check": "^2.5.1",
     "mocha": "^2.3.4",