chore(package): update concurrently to version 5.1.0

Closes #148

Author: greenkeeper[bot]

package.json

@@ -75,7 +75,7 @@
     "babel-preset-react-optimize": "^1.0.1",
     "babel-preset-stage-0": "^6.24.1",
     "bundlesize": "^0.17.0",
-    "concurrently": "^4.0.0",
+    "concurrently": "^5.1.0",
     "copy-webpack-plugin": "^4.0.1",
     "cross-env": "^5.1.4",
     "cross-spawn": "^6.0.5",