First init post types, higher priority (from 20 to 0).

Priotiry of the initial post types function should be set to < 10

@see https://core.trac.wordpress.org/ticket/28488
@see https://core.trac.wordpress.org/changeset/29318

@see https://github.com/WordPress/WordPress/blob/4.0/wp-includes/post.php#L167
Adjusted tested up to Easy Digital Downloads version.