added 'the_post'-action to ajax_load_purchased_content

Allow modifications to be made after the post has been loaded from the database. It is called by default in the setup_postdata function, which is invoked for every post during the_loop, to setup the global $post-variable.
Merge pull request #524 from derapU/feature/the_post_action_for_ajax_content

added 'the_post'-action to ajax_load_purchased_content
nice one.