Synchronize Migrants video with server clock

- includes time-server.js, to be run with nodejs as the clock server
- sockets.io port is hard-coded at 8081 for now. We'll likely need to change that.

To install:
- you need to have [nodejs and npm installed](http://blog.nodeknockout.com/post/65463770933/how-to-install-node-js-and-npm)
- in terminal, cd into the repo
- run `npm install` to install required node modules

To run:
- `node time-server.js`