Update with GOV.UK Frontend 0.0.32

[kr8n3r]

Changes

• Update to GOV.UK Frontend 0.0.32
• Remove vendored Frontend and gitignore node_modules
• Update sass with function, variable and mixin changes in Frontend
• Add app prose-scope to docs so that markdown-generated pages are styles
• Remove outdated partial code example and update with macros
• Update all pages with template blocks and remove redundant html structure
• Fix #57

[joelanman]

There are a bunch of references to Frontend being included in the codebase in the check for node_modules in start.js:

https://github.com/alphagov/govuk-prototype-kit-private-beta/blob/update-to-frontend-0.0.32/start.js

They should probably be updated in this PR which removes Frontend from the codebase