Add basic stylesheets, configure asset pipeline.
Update govuk_frontend_toolkit, add missing images.

Rails 4.1 raises an error if stylesheets reference images that don't exist.
Add layout and reset stylesheets, tweak wrappers.
Add specific stylesheet for contact show page.

Styles mainly copied over from hmrc-contacts app, but some styles and spacing
have been updated to look better - in particular, the phone number details are
wrapped in extra divs to add separation between different groups, and h3/h4
added to subheadings.
Add govspeak styles and wrappers.

This app does not itself process govspeak, it simply outputs pre-rendered HTML
from the content store. But that HTML might include any of the govspeak styles
in several fields since the admin enables govspeak for those fields.