Define minimum Node.js version

Author: paazmaya

index.js

@@ -4,5 +4,5 @@ var scriptPath = __dirname+'/build/HTMLCS.js';
 if (fs.existsSync(scriptPath) === true) {
     module.exports = require(scriptPath);
 } else {
-    throw new Error('HTMLCS must be built using `grunt build` before it can be required in Nodejs.');
-}
+    throw new Error('HTMLCS must be built using `grunt build` before it can be required in Node.js.');
+}

package.json

@@ -9,8 +9,12 @@
   ],
   "scripts": {
     "prepack": "grunt build",
+    "build": "grunt build",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "engines": {
+    "node": ">=6"
+  },
   "files": [
     "Auditor",
     "build",