npm package has src/ rather than build/

Summary:
We use custom npm scripts (`prepare-release`, `cleanup-release`) to

- move `src` to `src.orig`, and `build` to `src` before creating the tarball
- move everything back afterwards

We run these scripts with lerna before and after publishing. Custom hooks avoid problems with `prepublishOnly` and `postpublish` not being run at opportune times, `prepack` and `postpack` not being supported by npm v4 and yarn, and using `lerna run prepublishOnly` resulting in duplicated execution of the command.

This ensures that development is closer to what is pulled in from npm.

Reviewed By: jeanlauliac

Differential Revision: D5310133

fbshipit-source-id: 6b9885c88b936ef3fe5f1858738ad63d581a8731

lerna.json

@@ -1,6 +1,6 @@
 {
-  "lerna": "2.0.0-beta.38",
   "version": "0.8.1",
+  "lerna": "2.0.0-rc.5",
   "npmClient": "yarn",
   "packages": [
     "packages/*"

package.json

@@ -43,7 +43,8 @@
     "lint": "eslint . --cache",
     "lint-fix": "eslint . --fix --cache",
     "postinstall": "node ./scripts/postinstall.js && node ./scripts/build.js",
-    "publish": "yarn run build-clean && yarn run build && lerna publish",
+    "publish": "yarn run build-clean && yarn run build && lerna run prepare-release && lerna publish",
+    "postpublish": "lerna run cleanup-release",
     "test-ci": "yarn run typecheck && yarn run lint && yarn run build && yarn run jest-coverage -- -i && node scripts/mapCoverage.js && codecov",
     "test": "yarn run typecheck && yarn run lint && yarn run build && yarn run jest && yarn run test-examples",
     "typecheck": "flow check",

packages/metro-bundler/.npmignore

@@ -1,4 +1,5 @@
 **/__mocks__/**
 **/__tests__/**
-src
+build
+src.real
 yarn.lock

packages/metro-bundler/package.json

@@ -2,11 +2,15 @@
   "version": "0.8.1",
   "name": "metro-bundler",
   "description": "🚇 The JavaScript bundler for React Native.",
-  "main": "build/index.js",
+  "main": "src/index.js",
   "repository": {
     "type": "git",
     "url": "git@github.com:facebook/metro-bundler.git"
   },
+  "scripts": {
+    "prepare-release": "test -d build && rm -rf src.real && mv src src.real && mv build src",
+    "cleanup-release": "test ! -e build && mv src build && mv src.real src"
+  },
   "dependencies": {
     "absolute-path": "^0.0.0",
     "async": "^2.4.0",