Apply CSS coding contentions
Vendor prefixes are correctly ordered
Remove non existing vendor prefixes
 is implemented in browsers supporting it
Add to Homescreen module doesn't need vendor prefixes other than webkit since this is iOS-only
Use a mixin to remove box shadows
Merge branch 'master' of github.com:guardian/frontend into css-coding-conventions

Conflicts:
	common/app/assets/stylesheets/module/experiments/_story.scss
Merge pull request #928 from guardian/css-vendor-prefixes-ordering

Css vendor prefixes ordering
Whitespace
Merge branch 'css-coding-conventions' of github.com:guardian/frontend into css-coding-conventions
Merge branch 'master' of github.com:guardian/frontend into css-coding-conventions
Merge pull request #927 from guardian/css-coding-conventions

Apply CSS coding conventions