chore(package): update karma to version 3.1.3

Closes #64

Author: greenkeeper[bot]

package.json

@@ -21,7 +21,7 @@
     "grunt": "^1.0.1",
     "grunt-closure-tools": "^1.0.0",
     "grunt-contrib-concat": "^1.0.1",
-    "karma": "^1.3.0",
+    "karma": "^3.1.3",
     "karma-chrome-launcher": "^2.2.0",
     "karma-espower-preprocessor": "^1.1.0",
     "karma-firefox-launcher": "^1.0.1",