Update to latest version of babel and remove node version

[jodiedoubleday]

What does this PR do? (please provide any background)

• Updates to Babel 6
• Removes the engine dependencies from package.json
• Changes CI tooling to use 5.1 or latest stable version

  What tests does this PR have?

None

How can this be tested?

Delete the UIToolkit from you machine then clone it again. If you don't do this it will unfortunately fail to build. npm install npm run docs check the docs looks as good and work as well as they do on ui-toolkit.com You will have no console errors

Screenshots / Screencast

None

What gif best describes how you feel about this work?

---

• [x] I have checked our general contributing document and the project specific contributing document (if present) and I'm happy for this to be reviewed.

  Reviewers

Review 1

• [x] :+1:

Review 2 *

• [ ] :+1:

Review 3 (optional)

• [ ] :+1:

By adding a +1 you are confirming you have...

• Witnessed the work behaving as expected (this could be on the author's machine or screencast).
• Checked for coding anti-patterns.
• Checked for appropriate test coverage.
• Checked all the tests are passing.

* for HX this review must be completed by an SE, SA or Project Guru

[elliottcrush]

Had some issues installing, 'turning it off and on again' seemed to work though. Looks good :+1:

[Joezo]

Reviewing this

[Joezo]

Followed all the steps and still got an error when building :(

Running "shell:docsBuild" (shell) task

> ui-toolkit-docs@0.0.0 build /Users/joe.warren/repos/ui-toolkit/docs
> ./scripts/build.sh

Building docs
Error: Cannot find module 'babel-runtime/helpers/to-consumable-array' from '/Users/joe.warren/repos/ui-toolkit/node_modules/react-a11y/dist'

[hxpaul]

you have conflicts here

[hxpaul]

Also I get the same error as Joe when trying to build

Cannot find module 'babel-runtime/helpers/to-consumable-array' from '/Users/paul.clarke/work/ui-toolkit/node_modules/react-a11y/dist'

error in the ui-toolkit-docs I think rather than the ui-toolkit