Closes #6. Add Example with Flow

Author: Jared Palmer

examples/with-flowtype/.babelrc

@@ -0,0 +1,8 @@
+{
+  "presets": [
+    "backpack-core/babel"
+  ],
+  "plugins": [
+    "transform-flow-strip-types"
+  ]
+}

examples/with-flowtype/.flowconfig

@@ -0,0 +1,8 @@
+[ignore]
+.*/node_modules/invariant/.*
+
+[include]
+
+[libs]
+
+[options]

examples/with-flowtype/.gitignore

@@ -0,0 +1,3 @@
+node_modules
+build
+npm-debug.log

examples/with-flowtype/README.md

@@ -0,0 +1,19 @@
+# FlowType Example
+
+## How to use
+Download the example (or clone the whole project)[https://github.com/palmerhq/backpack.git]:
+```bash
+curl https://codeload.github.com/palmerhq/backpack/tar.gz/master | tar -xz --strip=2 backpack-master/examples/with-flowtype
+cd with-flowtype
+```
+Install it and run:
+```bash
+npm install
+npm run dev
+```
+
+## Idea behind the example
+This demonstrates how to add [Flow](https://flowtype.org/) to your Backpack project. Flow is a static type checker that helps you write code 
+with fewer bugs. Check out this [introduction to using static types in JavaScript](https://medium.com/@preethikasireddy/why-use-static-types-in-javascript-part-1-8382da1e0adb) if you are new to this concept.
+
+To learn more about Flow, take a look at [its documentation](https://flowtype.org/).

examples/with-flowtype/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "backpack-examples-with-flowtype",
+  "version": "0.0.6",
+  "scripts": {
+    "start": "node ./build/main.js",
+    "flow": "flow",
+    "dev": "backpack dev",
+    "build": "backpack build",
+    "postinstall": "backpack build"
+  },
+  "license": "MIT",
+  "dependencies": {
+    "express": "^4.14.0"
+  },
+  "devDependencies": {
+    "babel-plugin-transform-flow-strip-types": "^6.21.0",
+    "backpack-core": "0.0.6",
+    "flow-bin": "^0.37.4"
+  }
+}

examples/with-flowtype/src/index.js

@@ -0,0 +1,9 @@
+/* @flow */
+
+// This will throw an error when you run `npm run flow`.
+// change the return type to `:number`, to remove the error.
+function foo(x: string, y: number): string {
+  return x.length * y;
+}
+
+console.log(foo("Hello", 42));