Refactor: modr8 api functions

Refactor the code to provide a couple of nice, clean public api functions.

In my mind, this would be at least:
- modr8_moderate_node($node) - place a node into moderation
- modr8_approve_node($node) - approve and publish a node
- modr8_delete_node($node) - delete a node and notify user

The last 2 should be exactly what happens when clicking on the coorresponding button in the modr8 interface.