Show compile time

Created by: alexnewmannn

Hey, Apologies if it's been asked before but the issue uses very generic terms and I can't find any code for it, or any issues. But is it possible to show how long each compile takes, for example. "Compiled successfully in 1234ms" I guess https://github.com/facebookincubator/create-react-app/blob/2069e8ac43c4765f1698091d3985ecb70ba88089/packages/react-scripts/scripts/build.js#L75

I can potentially have a look at this and see how other plugins do it, but wondered if it was possible already and if its a desired feature.

Cheers!

edit: I did this work so I could use it locally, I've also submitted a Pull Request if this is of interest to you, below are some screenshots