Add support for launching application with `grunt server`

- Adds grunt and required plugins to package.json.
- Adds a Gruntfile.js with a "server" task to launch mongod and the
  node app.js file.
- Use nodemon to monitor changes to app.js, and any files in
  /lib, /modules, /routes, and automatically restart the server if
  any of them change.

This simplifies launching the app to just `grunt server`, and automatically restarts the server anytime the server code changes.