Upgrade FET to get new grid helpers
Use the new frontendtookit grid helpers

These are a better version of the app specific grid
helpers used before, which can be removed entirely.

This basically replaces;
 - `@grid-container` with `%site-width-container`
 - `@grid-outdent` with `%outdent-to-full-width`

Overrides to the default styling provied by
`govuk_template` and `static` (via `slimmer`) have
been moved into their own scoped SCSS modules to
separate application SCSS from tweaks to external
SCSS.

The later should be easy to identify, should
external SCSS change and the override need updating.

It also documents where external SCSS defaults
aren't working for this app, and how the overrides
could be merged into the original SCSS.
Merge pull request #2 from dsingleton/use-new-toolkit-grids

Use the new govuk_frontend_tookit grid helpers
Serve local assets on prod, eg, heroku
Add a startup script with ENV defaults, to make this easier to run
Static now applies bottom border to #footer, not #wrapper

This override isn't needed once https://github.com/alphagov/static/pull/473
is deployed, and as this is a prototype-y app i'm going to make the
change now.
Serve any root template by name

Allows easy adding of templates in welcome/ without havig to
add new routes and/or controllers
WIP smart answer questions, minimal layout

Gets rough markup in, to show default styling. Adds some special casing for
main content vs sidebar, but mostly generic.

Still needs
- Simplified markup
- next steps
- proper sidebar
- previous questions
- switching to header_footer_only