Remove node version from published package

[interactivellama]

This is a client side UI library, not a node library. Distributed package tags should not have a node limitation. Dev environment should however just for consistency.

I suggest:

"devEngines": {
    "node": "4.x || 5.x || 6.x || 7.x || 8.x",
    "npm": "2.x || 3.x || 4.x || 5.x"
  },

and that be removed on package/tag build. This will mean no node version demands for NPM/tag package.

Although we may want a <.10 for CJS. I will look into this when #1146 is worked on.

Nevermind devEngines is a yarn spec. We could just leave it up to the devDependencies to scream if they need a node version.

Background on why it's 6.x. #1011 It's related to a CI fail with Node 8.x

[interactivellama]

Fixed by #1176