commons_groups_group_submission_message() should check if node is published after form submission

You already did a check if the node was published, but you did it in the form_state (I guess you were tired :P). Here I removed the $node->status in the form_alter. I'm not 100% sure it's the best idea to check for the state of the status in the form_state.

I know _validate checked if it was a good value, but let's say someone is using to hook_insert() to play around the status variable, we would still output the message.

I could use the hook_insert myself, but I feel like it doesn't belong there and it's overkill. What do you think?