Add sinon as a dev dependency

package.json

@@ -27,6 +27,7 @@
     "jshint": "~2.5.1",
     "nomnom": "~1.6.2",
     "phantomjs": "~1.9.7-5",
+    "sinon": "~1.10.2",
     "taffydb": "~2.7.0",
     "temp": "~0.7.0",
     "underscore": "~1.6.0",

test/index.html

@@ -12,7 +12,7 @@
   <script type="text/javascript" src="jquery-1.9.1/jquery.min.js"></script>
   <!-- Extended expect.js w/ various methods, see #374 for the differences to 0.2.0 -->
   <script type="text/javascript" src="expect-0.2.0-ol3/expect.js"></script>
-  <script type="text/javascript" src="sinon-1.6.0/sinon.js"></script>
+  <script type="text/javascript" src="../node_modules/sinon/pkg/sinon.js"></script>
   <script type="text/javascript" src="mocha-1.8.1/mocha.js"></script>
   <script type="text/javascript" src="test-extensions.js"></script>
   <script>