Merge pull request #495 from noesya/features/previews

...ication/blocks/templates/call_to_action/_preview.html.erb

.../communication/blocks/templates/chapter/_preview.html.erb

...ommunication/blocks/templates/datatable/_preview.html.erb

...munication/blocks/templates/definitions/_preview.html.erb

...in/communication/blocks/templates/files/_preview.html.erb

...in/communication/blocks/templates/image/_preview.html.erb

...munication/blocks/templates/key_figures/_preview.html.erb

...ion/blocks/templates/organization_chart/_preview.html.erb

...in/communication/blocks/templates/pages/_preview.html.erb

...communication/blocks/templates/partners/_preview.html.erb

...unication/blocks/templates/testimonials/_preview.html.erb

...communication/blocks/templates/timeline/_preview.html.erb

...in/communication/blocks/templates/video/_preview.html.erb