Add cycleway shields for bike overlay

[nvkelso]

Once cycle networks are included in Mapzen vector tiles we can add special shields for them. Feedback from bike map launch.

Blocked by: https://github.com/tilezen/vector-datasource/issues/1175.

• [x] Functional
• [x] Polish
• [ ] Bug fixes

[nvkelso]

This is on dev, removing blocked from title.

[nvkelso]

Technically this is on dev, but seems broken.

[nvkelso]

Done