chore(package): update nyc to version 15.0.0

Closes #52

Author: greenkeeper[bot]

package.json

@@ -77,7 +77,7 @@
     "karma-webpack": "1.8.0",
     "mkdirp": "0.5.1",
     "mocha": "3.2.0",
-    "nyc": "10.0.0",
+    "nyc": "15.0.0",
     "phantomjs-prebuilt": "2.1.14",
     "rimraf": "2.5.4",
     "rollup": "0.38.1",