need to require('../app') for supertest to work

see details here:  http://stackoverflow.com/questions/25300204/how-do-i-set-up-express-with-mocha-and-supertest-for-integration-testing
I made the simplest possible example with supertest and express here: https://github.com/ultrasaurus/test-first-express/tree/supertest-1
updating README with the change that I had to make to my code.  If this is not the recommended path, please let me know what is.