chore(package): update ava to version 1.2.0

Closes #7

Author: greenkeeper[bot]

package.json

@@ -25,7 +25,7 @@
   },
   "devDependencies": {
     "async": "^2.5.0",
-    "ava": "^0.23.0",
+    "ava": "^1.2.0",
     "coveralls": "^3.0.0",
     "nyc": "^11.3.0",
     "standard": "^10.0.2"