Overview
Allow users to supply the original created date when first publishing a post.
Background
This is especially important for importing older posts, but is also useful for clients that want to support a scheduled post feature.
Implementation
If a created parameter exists on the SubmittedPost object, we'll insert that into the database instead of NOW().
If the date is after time.Now() and federation is enabled, do not federate the post.
Documentation
This should also get updated in the API docs.