Gérer les abonnements aux bulletins

                                                                             
 88888888888   88888888ba,             88   88b           d88   88888888ba   
 88            88      `"8b            88   888b         d888   88      "8b  
 88            88        `8b           88   88`8b       d8'88   88      ,8P  
 88aaaaa       88         88           88   88 `8b     d8' 88   88aaaaaa8P'  
 88"""""       88         88           88   88  `8b   d8'  88   88""""""'    
 88            88         8P           88   88   `8b d8'   88   88           
 88            88      .a8P    88,   ,d88   88    `888'    88   88           
 88            88888888Y"'      "Y8888P"    88     `8'     88   88