nextbus2pg code doesn't follow style guidelines

[XtremeCurling]

The first working version of nextbus2pg was written greatly prioritizing speed over code quality for primarily two reasons:

1. having a store of real-time vehicle location data is the core dependency for all future work;
2. I wanted to start collecting data before the Twin Peak Tunnel closure took effect.

However, the low code quality and lack of packaging likely make it difficult for other users to use or otherwise interface with this module.

To address this issue, redesign the scripts to better follow best-practice guidelines, e.g. http://columbia-applied-data-science.github.io/pages/lowclass-python-style-guide.html. In particular:

1. Turn this module into a proper package.
2. Improve user experience by simplifying and better explaining the steps needed to start collecting and storing data. A robust README is the most immediate requirement here.
3. Consider rewriting the module according to object-oriented design principles.