devkit: engines section similar to amber and cli

external/amber-dev/package.json

@@ -9,6 +9,9 @@
     "type": "git",
     "url": "git://github.com/amber-smalltalk/amber.git"
   },
+  "engines": {
+    "node": "0.10.x || 0.12.x || >=4.0.0"
+  },
   "author": "",
   "license": "MIT",
   "bugs": {