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.
$account usually indicates it's not the global $user -- so one can freely pass it to other functions.

I think it would be a better practice to delcare ``global $user;`` on top of the function and use it here:

``if ($user->uid !== $message->user->getIdentifier()) {``

(also, I think the typecasting isn't really needed here)