adding command for G2 East from the DC office

so this is fairly horrible, I know, and introduces two new dependencies. in my defense:

- the code was written for a raspberry pi project, which is why there's a bunch of extraneous "let's not hammer the server" stuff I haven't bothered to factor out
- Nextbus does not include DC properly in its API, which is why this is a screen-scraper
- However, it uses static HTML from the legacy site, so this might break at some point
- New routes/stops are relatively simple to add (and should be added!) by fiddling around with the querystring params.