Upgrade to yarn 1.0.1 for node 8.4

[shouze]

As it fixes many many things, notably some weird bin links regression.

[SimenB]

We only update yarn in new releases of node so that we don't change the yarn version for folks from under their feet.

https://github.com/nodejs/docker-node/blob/17c50cb300581280805a4183524fbf57840f3a7e/CONTRIBUTING.md#version-updates

Unlikely to change unless you have a good reason to? #393 (comment)

Thanks for the PR though!

[shouze]

@SimenB I understand thx to pointing me to CONTRIBUTING about that, I should have checked it by myself.

[SimenB]

No problem 🙂

[SimenB]

@nodejs/docker we could add github templates (at least for PRs) that states this fact (when we update yarn/npm)? The link GitHub generates if a CONTRIBUTING is present is very easy to overlook - actually having to delete the text content of the OP is more explicit.

[chorrell]

Yeah I'd like to see templates in place to spell out things like that. I'm sure there are other policies we could put in there...like something that explains how things land in the docker-hub would be good too :) It's not really obvious to many people how the images ultimately get to the hub and all the steps involved.