Update dependencies to enable Greenkeeper 🌴 (#10)

Author: greenkeeper[bot]

README.md

@@ -4,6 +4,7 @@
 [![NPM downloads][downloads-image]][downloads-url]
 [![Build status][travis-image]][travis-url]
 [![Test coverage][coveralls-image]][coveralls-url]
+[![Greenkeeper badge](https://badges.greenkeeper.io/blakeembrey/javascript-stringify.svg)](https://greenkeeper.io/)
 
 > Stringify is to `eval` as `JSON.stringify` is to `JSON.parse`.
 

package.json

@@ -26,8 +26,8 @@
   "license": "MIT",
   "readmeFilename": "README.md",
   "devDependencies": {
-    "chai": "^1.9.1",
-    "istanbul": "^0.3.0",
-    "mocha": "^1.21.3"
+    "chai": "^3.5.0",
+    "istanbul": "^0.4.5",
+    "mocha": "^3.3.0"
   }
 }