Fix absolute path for logs

Correction du bug qui affiche ce message d'erreur en haut de chaque page : 

> Warning: mkdir(): Permission denied in /data/www/ifaedi/html/commun/php/log4php/appenders/LoggerAppenderFile.php on line 72
> 
> Warning: fopen(/home/aedi/Documents/IFAEDI/S.I/Serveur/web/logs/my.log): failed to open stream: No such file or directory in /data/www/ifaedi/html/commun/php/log4php/appenders/LoggerAppenderFile.php on line 76