App Base Class

- Added lib/App with basic lifecycle events and extend method
- Added index.js that exports App
- Added tests for App and Module API

I didn't add the package.json because I figured you wanted to set that up yourself.  To get the tests running I did this:

- `npm install should sinon underscore`
- If you don't have mocha: `npm install -g mocha`
- `mocha -r should test/*_spec.js -R spec`