Bumps devDependencies

Author: peterramsing

package.json

@@ -27,10 +27,10 @@
   "devDependencies": {
     "chai": "^3.5",
     "clean-css": "^4.1.6",
-    "codecov": "^2.1.0",
+    "codecov": "^3.0.2",
     "eslint": "^3.16",
-    "mocha": "^3.2",
-    "nyc": "^10.3.2"
+    "mocha": "^5.2.0",
+    "nyc": "^13.0.0"
   },
   "scripts": {
     "test": "nyc mocha",