chore(package): update nyc to version 12.0.2

Closes #49

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
   "devDependencies": {
     "ava": "^0.20.0",
     "coveralls": "^2.13.1",
-    "nyc": "^11.0.3",
+    "nyc": "^12.0.2",
     "spike-core": "^2.0.1",
     "standard": "^10.0.0"
   },