Connection/Disconnection

1. Connection
   The connection procedure is defined as follows :

   <connexion>
     <persoin supercontext="persoin">
       <instruction>Sélectionnez la personne concernée</instruction>
     </persoin>
     <store model="groups" supercontext="_groups" type="erase" />
   </connexion>
   

2. Disconnection procedure is defined as follows :

   <deconnexion>
     <clean supercontext="_groups"/>
     <clean supercontext="persoin"/> 
   </deconnexion>