Update travis + prettier stuff.

[ryan-roemer]

So, we integrated prettier (yay!), but we forgot to apply prettier to everything already in Spectacle (boo!). Our husky / precommit integration only runs prettier on git staged files, leaving a broad hole of everything else that isn't prettier compliant before.

This PR fixes this as follows:

• Add a prettier check to CI to fail CI if notwithstanding lint-staged, non-prettier compliant changes somehow get in a PR
• Adds some yarn run prettier-fix and yarn run lint-fix helpers (wrappers) for devs to be able to easily tune things.
• Updates travis to 10, removes 9 (we needed a minor yarn.lock resolution update to support this too for upath)
• Update jest snapshots (Thanks @blainekasten !!!!)
• Separate minor thing: Remove __mocks__ from published package. Fixes Infra: Remove __mocks__ from npm publishing. #537

[ryan-roemer]

As expected, failed with:

> spectacle@4.2.3 prettier /home/travis/build/FormidableLabs/spectacle
> prettier "**/*.{js,json,css,md}" "--list-different"
docs/basic-concepts.md
docs/extensions.md
docs/getting-started.md
docs/props.md
docs/tag-api.md
example/src/index.js
index.js
README.md
server.js
src/components/anim.js
src/components/appear.js
src/components/autoplay-controls.js
src/components/block-quote.js
src/components/block-quote.test.js
src/components/cite.js
src/components/clock.js
src/components/code-pane.js
src/components/code-pane.test.js
src/components/code.js
src/components/code.test.js
src/components/component-playground.js
src/components/component-playground.test.js
src/components/controls.js
src/components/controls.test.js
src/components/deck.js
src/components/export.js
src/components/fullscreen-button.js
src/components/fullscreen.test.js
src/components/go-to-action.js
src/components/go-to-action.test.js
src/components/heading.js
src/components/heading.test.js
src/components/image.js
src/components/layout.js
src/components/layout.test.js
src/components/list-item.test.js
src/components/list.js
src/components/list.test.js
src/components/magic-wrapper.js
src/components/magic.js
src/components/manager.js
src/components/manager.test.js
src/components/markdown-slides.js
src/components/markdown-slides.test.js
src/components/markdown.js
src/components/markdown.test.js
src/components/notes.test.js
src/components/overview.js
src/components/presenter-components.js
src/components/presenter.js
src/components/presenter.test.js
src/components/progress.js
src/components/quote.test.js
src/components/s.js
src/components/s.test.js
src/components/slide-components.js
src/components/slide.js
src/components/slide.test.js
src/components/table-body.js
src/components/table-body.test.js
src/components/table-header-item.test.js
src/components/table-header.js
src/components/table-header.test.js
src/components/table-item.test.js
src/components/table-row.js
src/components/table-row.test.js
src/components/table.test.js
src/components/text.js
src/components/time-components.js
src/components/time.js
src/components/timer.js
src/components/typeface.js
src/components/typeface.test.js
src/one-page.js
src/reducers/fragment.js
src/reducers/route.js
src/reducers/style.js
src/sync/__mocks__/index.js
src/sync/index.js
src/themes/default/print.js
src/themes/default/prism.dark.js
src/themes/default/prism.light.js
src/themes/default/screen.js
src/utils/base.js
src/utils/context.js
src/utils/controller.js
src/utils/fullscreen.js
src/utils/magic.js
src/utils/preloader.js
src/utils/slides.js
src/utils/slides.test.js
src/utils/step-counter.js
src/utils/types.js
webpack.config.js
webpack.config.production.js
webpack.config.umd.js
webpack.config.umd.production.js

Then noticed that node10 on travis failed because of upath having a curious >4 <9 node dep. Regen'ed yarn.lock which picks up a fix, but then got new lint errors for react deprecating stuff.

Plan is to "go forward" and fix lint too.