Build step in preparation for flow integration

Summary:
It only strips out flow types and puts all .js files into `/build/*` directory

also moved stuff around in the root directory. All build/test/setup related files now are in `./scripts/*`

<img width="605" alt="screen shot 2016-06-03 at 8 18 05 pm" src="https://cloud.githubusercontent.com/assets/940133/15797324/79d4d8c2-29c8-11e6-8910-746bb6e5b92c.png">
Closes jestjs#1113

Differential Revision: D3426709

fbshipit-source-id: fe585d557d53dcce4b23af0538c861b5d1ac292e

.eslintignore

@@ -4,3 +4,4 @@ docs/
 **/vendor/**
 website/
 **/coverage/**
+packages/*/build/**

.gitignore

@@ -5,9 +5,9 @@
 /node_modules
 /examples/*/node_modules/
 /packages/*/node_modules/
+/packages/*/build/
 /website/node_modules
 npm-debug.log
-build
 website/core/metadata*.js
 website/src/jest/docs
 website/src/jest/blog

package.json

@@ -1,16 +1,20 @@
 {
   "private": true,
   "devDependencies": {
+    "babel-core": "^6.9.1",
     "babel-eslint": "^6.0.4",
+    "babel-plugin-transform-flow-strip-types": "^6.8.0",
     "eslint": "^2.10.2",
     "eslint-plugin-babel": "^3.2.0",
     "fbjs-scripts": "^0.7.0",
+    "glob": "^7.0.3",
     "lerna": "2.0.0-beta.10",
+    "minimatch": "^3.0.0",
     "rimraf": "^2.4.4"
   },
   "scripts": {
     "lint": "eslint .",
-    "postinstall": "node postinstall.js",
-    "test": "npm run lint && node ./runTests.js"
+    "postinstall": "node ./scripts/postinstall.js",
+    "test": "npm run lint && node ./scripts/test.js"
   }
 }