centralize husky code

[xavdid]

The actual content of this is:

• remove prettier from devDeps (stays in cli since it's used in scaffold)
• remove husky, lint-staged, and their configuratioon from all packages
• per the docs, only run husky in the root.

the exported schema json got run through prettier again and the formatting changed. we jumped a number of minor versions, so something must have changed. In any case, stepped through the command and confirmed that what's in this PR is the output of prettier v1.18.2, so ¯\_(ツ)_/¯

[xavdid]

Build is failing because yarn is complaining about an incompatible version, which must have come in from an updated dependency.

I ran yarn --ignore-engines locally on node 8 and all the tests passed with no issue.

[eliangcs]

Thanks for setting this up!

Looks like execa requires Node.js >= 8.12 only because here it uses until.getSystemErrorName, which isn't available until Node.js 8.12. I guess it's safe to ignore. Can you add --ignore-engines to the test command(s) accordingly so the tests can be run on CI? Feel free to merge once addressed.

[xavdid]

sweet, that did it! also needed to add AWS_SECRET_ACCESS_KEY=fake (same for secret) on the repo settings. It was doubly confusing because there's 2 identical settings pages (travis-ci.org and .com), but only one affects builds (.com). Got it now though!

[eliangcs]

@xavdid that was my bad. I actually removed the ones on travis.com as I thought they're useless. Anyway, I think it's better to put the keys in package.json rather than on Travis. Addressed in #35.