Adding GalleryCTA Test
Adding double arrows
gallerythumbs.css is more appropiate for these styles
Adding AB test
Adding A/B test doc
Typo
Merge branch 'master' into ab-gallery-cta

Conflicts:
	common/app/assets/javascripts/modules/experiments/ab.js
Updated doc
Update gallery-cta-style.md
Removing redundant styles
Merge branch 'ab-gallery-cta' of github.com:guardian/frontend into ab-gallery-cta

Conflicts:
	docs/experiments/gallery-cta-style.md
Use link as the CTA - gallery code expects a link to an image
Merge pull request #1429 from guardian/ab-gallery-cta

A/B test - Gallery call to actions