Add kwargs to roadway

[e-lo]

Problem

As a user, I need to be able to specify various parameters for my RoadwayNetwork such as CRS and foreign IDs

Solution

Re-orients previous class-Level hardcoded-variables to module-level defaults which can be set upon RoadwayNetwork class instantiation.

Fixes #290

Considerations for reviewers:

• Should we do this for Transit as well - separate issue?
• Are the "defaults" currently appropriate?

[DavidOry]

There are a number of cosmetic changes here, e.g., link_file to link_filename. Can we separate these into a separate PR?

[e-lo]

Closing this as we have aligned over a more strict model in selection-refactor branch.