Specify a files array for NPM

Author: blakeembrey

package.json

@@ -4,6 +4,10 @@
   "description": "Stringify is to `eval` as `JSON.stringify` is to `JSON.parse`",
   "main": "javascript-stringify.js",
   "typings": "javascript-stringify.d.ts",
+  "files": [
+    "javascript-stringify.js",
+    "javascript-stringify.d.ts"
+  ],
   "scripts": {
     "test": "istanbul cover node_modules/mocha/bin/_mocha -- -R spec"
   },