Refactor post_updated and wp_insert_post callbacks

[ilicfilip]

When post is published or updated we need to check if a new activity needs to be added, for that reason we hook into post_updated and wp_insert_post hooks and we have separate callbacks for them.

wp_insert_post is fired when post is inserted for the first time, but when post is updated both the post_updated and wp_insert_post are fired which makes both callbacks needlessly.

Quick fix would be to use the third parameter in the wp_insert_post ( (bool) $updated) and merge both callbacks in one function, something like this.