chore(package): update babel-preset-es2015 to version 6.13.1

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -31,7 +31,7 @@
     "ava": "^0.14.0",
     "babel-cli": "^6.4.0",
     "babel-eslint": "^6.0.2",
-    "babel-preset-es2015": "^6.3.13",
+    "babel-preset-es2015": "^6.13.1",
     "babel-register": "^6.4.3",
     "coveralls": "^2.11.6",
     "eslint": "^2.0.0",