Ensure current Configuration is passed to Page Types in Editor

After changing the page template, page type hooks were passed obsolete
configuration objects.
Fix Image 404 in Editor

Do not set background image url if no image is configured.
Merge pull request #204 from tf/page-preview-config

Ensure current Configuration is passed to Page Types in Editor
Merge pull request #203 from tf/fix-image-404-in-editor

Fix Image 404 in Editor