Add Map Settings (Flexible Service Windows)

*Work in progress*

This commit creates a __map settings__ area, where users can set default service windows, speed, etc. These are inherited by bus lines as they are created.

- [X] Add basic framework for settings inheritance
- [ ] Add speed, layover, cost per hour
- [ ] Store map settings in ruby backend 
- [ ] Add a "apply to all existing lines" button
- [ ] Design and style MapSettingsView
- [ ] Figure out good default windows and window times (ask transit planners)
- [ ] Figure out migration path for existing data