WIP : CFD-144 log group activity

Modules to support logging activity in the message table for:
* create/edit/delete node content.
* create/edit/delete comments.
* activities about users and group membership.
Thats true, but the node delete is called by node_delete(id); so you can't set the parameter to avoid the message being logged… (comment_delete, og_group, og_ungroup).

You could try to avoid this by calling the underlying functionality directly but does nog give you control messages triggered by called hooks…