Framework: Add lerna to publish @automattic/simple-components

Add `lerna` (a monorepo tool) to Calypso, and use it to publish [`@automattic/simple-components`](https://www.npmjs.com/package/@automattic/simple-components) as a separate npm.

This involves adding a `package.json`, `.gitignore`, and `.npmignore` to `client/components`, and an `alias` field to Calypso's webpack configs.

Since we want Calypso (and possibly other consumers) to continue to use untranspiled code (to benefit from features such as tree-shaking), the npms we produce should contain both transpiled and untranspiled versions of the code. See http://2ality.com/2017/07/npm-packages-via-babel.html, and for more information, http://2ality.com/2017/04/transpiling-dependencies-babel.html and http://2ality.com/2017/06/pkg-esnext.html.

client/components/.gitignore

@@ -0,0 +1,2 @@
+cjs
+node_modules

client/components/.npmignore

@@ -0,0 +1 @@
+node_modules

client/components/index.js

@@ -0,0 +1,9 @@
+/** @format */
+
+// Keep in sync with the `files` field in package.json!
+// TODO: Can we auto-generate at build time?
+
+export { Badge } from './badge';
+export { Button } from './button';
+export { Main } from './main';
+export { Notice } from './notice';

client/components/package.json

@@ -0,0 +1,45 @@
+{
+	"name": "@automattic/simple-components",
+	"version": "0.1.0-alpha.7",
+	"description": "React components, as used on WordPress.com",
+	"scripts": {
+		"build": "npx babel --only ./index.js,./badge/,./button/,./main/,./notice/ --out-dir cjs .",
+		"prepublishOnly": "npm run build"
+	},
+	"repository": {
+		"type": "git",
+		"url": "git+https://github.com/automattic/wp-calypso.git"
+	},
+	"keywords": [
+		"wordpress",
+		"react",
+		"components"
+	],
+	"author": "Automattic",
+	"license": "GPL-2.0+",
+	"bugs": {
+		"url": "https://github.com/automattic/wp-calypso/issues"
+	},
+	"homepage": "https://github.com/Automattic/wp-calypso/blob/master/docs/components.md",
+	"main": "./cjs/index.js",
+	"esnext": "./index.js",
+	"files": [
+		"index.js",
+		"cjs/",
+		"badge/",
+		"button/",
+		"main/",
+		"notice"
+	],
+	"dependencies": {
+		"classnames": "^2.2.6",
+		"gridicons": "^3.0.1",
+		"i18n-calypso": "^1.9.1",
+		"lodash": "^4.17.10",
+		"prop-types": "^15.6.2",
+		"react": "^16.4.1"
+	},
+	"publishConfig": {
+		"access": "public"
+	}
+}

lerna.json

@@ -0,0 +1,6 @@
+{
+  "packages": [
+    "client/components"
+  ],
+  "version": "independent"
+}