Refactor project structure (app and tests)

Express App:
  * rename main file to `app.js`
  * extract routes into a seperate file
  * export the app from the `app.js` file
  * start the server only if the app hasn't been required
  * setup app config file

Tests:
  * move test requires to mocha.opts
  * move fixture data into it's own directory
  * install Zombie.js for acceptance tests
  * setup test scaffold for routes
  * initial test for home page