chore(package): update ava to version 2.2.0

Closes #45

Author: greenkeeper[bot]

package.json

@@ -42,7 +42,7 @@
     "through2": "^2.0.1"
   },
   "devDependencies": {
-    "ava": "^0.24.0",
+    "ava": "^2.2.0",
     "babel-preset-es2015": "^6.18.0",
     "babelify": "^8.0.0",
     "catch-stdout": "0.0.1",