[Dev Deps] update `eslint`, `eslint-config-airbnb`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `eslint-plugin-react-hooks`, `eslint-plugin-react-with-styles`

[Dev Deps] update `@babel/*`, `@storybook/*`, `babel-plugin-inline-svg`, `babel-plugin-istanbul`, `babel-preset-airbnb`, `eslint-config-airbnb` to v18 (plus peer deps), `eslint` to v6; `eslint-plugin-react-with-styles`, `karma`, `karma-firefox-launcher`, `mocha`, `safe-publish-latest`, `sass-loader`, `sinon`, `sinon-sandbox`, `coveralls`, `enzyme-adapter-react-helper`

This will help reduce the bundle size impact. Note that any consumers
who are depending on any react-dates components having a `.propTypes`
property will no longer work as expected after this change.

I enabled this using wrap mode, which adds `process.env.NODE_ENV`
checks, which is a pretty standard method for React apps. I believe this
will allow this library to have propTypes in development, but for them
to be minified out in production builds.

To make this safe to enable in this repo, I enabled the
react/forbid-foreign-prop-types ESLint rule, which was written
specifically for the benefit of this plugin.

Here's a diff showing what effect this has on the esm build:

  https://gist.github.com/lencioni/1b436d365570394ccde659c829ba02c3

[Dev Deps] update `babel-loader`, `babel-preset-airbnb`, `eslint-plugin-jsx-a11y`, `node-sass`, `sinon`, `sinon-sandbox`

[Dev Deps] update `eslint-config-airbnb`, `eslint-plugin-import`, `eslint-plugin-react`, `coveralls`, `babel-plugin-inline-react-svg`, `airbnb-js-shims`, `@storybook/react`, `@storybook/addon-options`, `@storybook/addon-links`, `@storybook/addon-info`, `@storybook/addon-actions`, `sinon`, `sass-loader`

 - also update linting errors

[Dev Deps] update `sinon`, `moment`, `karma-webpack`, `eslint`, `eslint-config-airbnb`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `enzyme-adapter-react-15`, `enzyme`, `cross-env`, `coveralls`, `chai`, `babel-plugin-istanbul`, `aphrodite`

This will help prevent eslint from getting confused if there is a
.eslintrc in a higher directory.

These eslint rules will help protect this project from bad
react-with-styles usage.

[Dev Deps] update `babel-cli`, `babel-core`, `babel-register`, `eslint`, `eslint-plugin-react`, `sinon`; downgrade `babel-loader`

[Dev Deps] update `eslint`, `eslint-plugin-react`, `nyc`, `react-test-renderer`, ``json-loader`, `chai`, `cross-env`

Fixes #335.

[Dev Deps] update `webpack`, `sinon`, `sass-loader`, `safe-publish-latest`, `react`, `react-addons-shallow-compare`, `react-addons-test-utils`, `react-dom`, `moment`, `mocha-wrap`, `mocha`, `karma-webpack`, `karma-mocha`, `karma`, `eslint`, `eslint-config-airbnb`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `babel-cli`, `babel-core`, `babel-loader`, `babel-plugin-syntax-jsx`, `babel-preset-airbnb`, `babel-register`, `@kadira/storybook`, `coveralls`, `enzyme`

 - fix linting errors

Removes the short-lived tether dependency in react-dates in favor of just doing the thing internally

[Dev Deps] update `eslint`, `eslint-config-airbnb`, `eslint-plugin-react`, `eslint-plugin-jsx-a11y`, `eslint-plugin-import`, `mocha`, `mocha-wrap`, `sinon`, `git-directory-deploy`, `babel-core`, `babel-cli`, `babel-loader`