chore(package): update ava to version 2.0.0

Closes #29

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
     "lodash": "^4.17.4"
   },
   "devDependencies": {
-    "ava": "^0.23.0",
+    "ava": "^2.0.0",
     "babel-eslint": "^8.0.0",
     "eslint": "^3.10.2",
     "eslint-config-iansinnott": "^1.0.1",