chore(package): update ajv to version 6.5.3

Closes #10

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
     "grunt": "^1.0.1",
     "grunt-contrib-connect": "^1.0.2",
     "grunt-parts": "^0.5.6",
-    "ajv": "^5.4.0",
+    "ajv": "^6.5.3",
     "codecov": "^1.0.1",
     "eslint": "^4.11.0",
     "eslint-config-airbnb-base": "^10.0.1",