Add return $status to twitter_post_node_insert() for module_invoke()

I need to get the $status returned from twitter_post_node_insert() so when I call the hook with module_invoke() I can use the $status to build a link with _twitter_status_url() and then put that in the state_flow history block.

Now, I don't think this is the best way to do this but it works for my implementation and I want to post this to get feedback on a better way. I know I can strip out certain info from $_SESSION as that is where the messages are stored but that seems a bit on the hacky side.

Patch below, this depends on https://drupal.org/node/2022485#comment-7552403 as well for it to apply and to even make sense on why I would want to do this.