Add Content Scheduling

[lisandi]

It would be very beneficial if the scheduled post content for the stream would also work content created with the wiki module.

It would be good if the time for publishing the content and even the time for unpublishing the content could be set while creating a wiki page.

Use Case:
A wiki is a collaborated space and we use it i.e. in schools and communities where members create content in form of a collaborative effort. But still there is a date when their works had to be finished and that would be the "scheduled Publish" date. and the same an unpublish date in case the content should get removed again after a certain time.

Good would be also to integrate an approval mechanism that only teachers or members with special permissions for the wiki could schedule and publish pages. This would make it also useful for News writers where the Newsreporters are actually the community members. A Chief editor would approve or send back to improve or not appove a wiki page before it would get scheduled by the chiefeditor to be published.