Work completed

This PR completes the coding challenge.

I've included stops.json and departures.json in the commit.

stops.json is a shortened version of all 1000+ stops, I've reduced it to two stops to make step 2 faster. I ran step 2 with:

`node run.js --extract departures --output departures.json --startdate 2014-01-16 --enddate 2014-01-16`