Updates to the 'start page' for 2018

[emilyashley]

• [ ] - create or update 'start a chapter' copy
• [ ] - create 'list a chapter' copy
• [ ] - typeform (yes / no / turn off for now?)
• [ ] - routing
• [ ] - update navbar header to say "list a chapter" instead of "start a chapter"

[emilyashley]

Merged in a wow outstanding PR today. Thinking about the remaining item notes on this ticket and follow up steps.

[emilyashley]

Updating maptime.io is blocked by me getting up a local instance. Come back to this after relevant substeps of https://github.com/maptime/maptime.github.io/issues/294