Add per-line service windows & upgrade stats UI

This pull request introduces a revamped UI and data structure for line statistics. Each line has a set of "service windows", which can have independent times and headways. This lets users create AM and PM peaks with more frequent buses.

This also emphasizes the calculated stats more strongly, and lets a user click to see and modify the numbers that go into that calculation. See screenshot below.

Some other things that snuck into this branch:

- Put your cursor in the "every" field and use up and down arrows to quickly shift values
- Fix for relative paths in rakefile
- Cleanup of router to prevent extra renders
- Cleanup of parse / toJSON in maps and lines
- Move front-end save logic from views to models
- More things.

![screen shot 2014-05-28 at 5 57 34 pm](https://cloud.githubusercontent.com/assets/1435836/3112935/45dac07c-e6cc-11e3-9e10-1a0e0866f1be.png)

![screen shot 2014-05-28 at 5 50 04 pm](https://cloud.githubusercontent.com/assets/1435836/3112925/f379aa0a-e6cb-11e3-9154-c74a2e423eb9.png)