Scrape National Rail for train departure data

- Needs to deal with arrivals too.
- This scrapes the National Rail website on every query, therefore
  can be stupidly slow. For small stations like Falmouth Docks, it's
  fine, but for big stations like Guildford, the request times out. I
  need to think about a sensible limit for number of stations to
  retreive, or only retreiving unique ones. I filter the array down
  to show only unique ones at view level.
- This is mailing an experiment in using Nokogiri and doing scraping.