Use program.js instead of server.js.

The instructions for the Routes exercise tell you to run/verify server.js. However, the instructions provided below by workshopper say to run/verify program.js (e.g. `To verify your program, run: makemehapi verify program.js`). This could be confusing to new users who don't realize this is meant to be the same file. This issue is similar to rvagg/learnyounode#97.