chore(package): update eslint-plugin-ava to version 4.2.0 (#247)

https://greenkeeper.io/

package.json

@@ -134,7 +134,7 @@
     "coveralls": "2.11.16",
     "cross-env": "3.1.4",
     "eslint": "3.15.0",
-    "eslint-plugin-ava": "4.1.0",
+    "eslint-plugin-ava": "4.2.0",
     "finis": "0.0.2",
     "fluent-ffmpeg": "2.1.0",
     "jsdoc-to-markdown": "^3.0.0",