pages: add cat and tag

Move image assets in `/assets/images`

Merge branch 'release/3.0.0'

Merge branch 'feature/remove-sample-files' into develop

Reduce config to bare minimum and remove sample content

Add layout to 404 page

Merge branch 'feature/documentation-and-demo' into develop

Update home splash page

Build home splash page

Update about page

Rename feature row include

Slugify tags

Fix path bugs in breadcrumbs

Simplify feature row SCSS

Merge branch 'feature/spit-and-polish' into develop

Add notes about feature_row type used

Build out overlay header and feature row _include helper

Add test content

Rough out splash page _layout with styles and test content

Merge branch 'feature/visual-refresh' into develop