An opinionated PR

- Add a build process (`gulp` in particular)
- Use `browserify` to package browser script, which will expose `window.Router` automatically
- Make `browser.js` inherits from `router.js`

For discussions:

- Right now server testing uses `vows` & browser uses `qunit`. Any chance of unifying them w/ `mocha` & `expect.js` or something? I wanna hook up either browserstack/sauce labs/phantomjs to this to automate build process.
- This library supports Node 0.4, yet testings stops at 0.8. Any chance of upping Node version support to 0.8?
- This library also uses ES5 functions (like `Array.isArray`), maybe we need some instructions on ES5shim requirements for <IE9 users?