chore(package): update ava to version 1.4.0

Closes #29

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
   },
   "devDependencies": {
     "babel-eslint": "^8.0.0",
-    "ava": "^0.23.0",
+    "ava": "^1.4.0",
     "eslint": "^3.10.2",
     "eslint-config-iansinnott": "^1.0.1",
     "eslint-config-zen": "^3.0.0",