Remove SVG fallback.
Remove Modernizr.svg.
Remove SVG fallback.

Remove checkbox.png fallback.
Merge pull request #1556 from vogdb/issue-1556

Remove SVG fallback
Remove .gradient mixin.
Update viewport-units-buggyfill from 0.4.2 to 0.5.0.
Merge pull request #1569 from vogdb/issue-1569

Update viewport-units-buggyfill from 0.4.2 to 0.5.0.
Merge pull request #1555 from vogdb/issue-1555

Remove .gradient mixin.
Merge branch 'master' of github.com:cargomedia/CM into issue-1564