unstyled -> u-unstyled
Extend placeholders, not classes
Add data files
Merge branch 'master' of github.com:guardian/frontend into unstyled-deprecate

Conflicts:
	data/database/11287e034bd7ddd5f731c8853a301fc01a542f7fe909b4947673cb190629ea59
	data/database/f6c41fd2e5bb82767f9d02f3ae00f797af7b4c60c7a4bfd0deb83cf47569f188
Merge pull request #3485 from guardian/unstyled-deprecate

Unstyled class deprecation