chore(package): update ava to version 3.4.0

Closes #20

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
     "lodash": "^4.17.4"
   },
   "devDependencies": {
-    "ava": "^0.25.0",
+    "ava": "^3.4.0",
     "axios": "^0.17.0"
   }
 }