Feature: train station + bus stop integration

[JasonBarahan]

Description

Most (if not, all) GO train stations also have bus stops within the same station complex, or within walking distance of the station property. The API treats train station departures and bus stop departures separately.

For example, Aurora GO has a bus loop, Cooksville GO has bus bays, and Union Station has its own bus terminal.

This feature integrates departures from train stations and bus stops associated with each station for simplicity, especially when train lines are substituted with bus service ('bustituted').

Caveats

• The API treats train station departures and bus stop departures separately. We will need to make separate API calls to the same endpoint and merge the JSON objects together, then sort them by time.
• Some GO stations have multiple bus stops associated with it (for example, Bramalea GO has three bus stops, each with their own ID and requiring their own API calls). This is presumably due to express bus services serving selected stations, in addition to multiple branches of the bus line serving the same station.
• The current implementation of 'next departure retrieval' only includes three departures. Considering some bus lines operate in conjunction with train service (for example, Lakeshore West service is complemented by express bus route 16 between Toronto and Hamilton) combining bus service may make returned information less useful to the user.