add parallel functions for bus tracker api

[willdebras]

Need to write parallel functions for gettime, getvehicles, getroutes, getdirections, getstops, getpatterns, getpredictions, and getservicebulletins requests found in this documentaiton:

https://www.transitchicago.com/assets/1/6/cta_Bus_Tracker_API_Developer_Guide_and_Documentation_20160929.pdf

[raybuhr]

Nice meeting you at CRUG event tonight. This is a cool package and I'm glad you made it.

I think there might be some function naming confusion in time, but will let you handle that. For this, I just followed your convention.

I created a few functions for most of the Bus Tracker API endpoints:

• get_bus_location() for current bus location
• get_bus_routes() for all bus routes
• get_bus_route_directions() to see if a route runs N-S, E-W, etc
• get_bus_route_stops() for all the bus stop locations

I did not get to a few endpoints:

• predictions
• patterns
• servicebulletins

I kind of wanted to document these to the README, but I think that might be another good future issue/PR. Also, I'm not really sure how you want to organize it. Might be better off just mentioning the bus functions and pointing to a vignette.

[willdebras]

Thank you so much Ray. This is awesome progress!! Nice meeting you as well. I'll review and merge this weekend when I'm home. Agree that function nomenclature gets confusing with both APIs so I'll rename the train ones to be explicitly get_train_x() or something like that.

I think it's probably worth changing the README with a couple examples from each API and then breaking the full documentation for the bus into a vignette and just linking to it.

Thanks again. This is awesome!

[raybuhr]

I added examples to the README and even found a missing httr:: call in my functions while doing so. I also updated the NEWS and DESCRIPTION (to bump version to 0.2.0) if that's cool with you.

[willdebras]

That's perfect! Thanks so much.