fix(package.json): update karma; fixed #3

Author: pine

package.json

@@ -21,7 +21,7 @@
   },
   "devDependencies": {
     "chai": "^4.1.2",
-    "karma": "^1.1.2",
+    "karma": "^2.0.0",
     "karma-mocha": "^1.1.1",
     "karma-mocha-reporter": "^2.0.4",
     "karma-phantomjs2-launcher": "^0.5.0",