chore(package): update sinon to version 4.1.5

Closes #28

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "rollup-plugin-node-resolve": "3.0.0",
     "rollup-plugin-sourcemaps": "^0.4.1",
     "rollup-plugin-uglify": "^2.0.1",
-    "sinon": "4.1.3"
+    "sinon": "4.1.5"
   },
   "keywords": [
     "router",