gistfile1.txt

function activate_plugin_via_php() {
       $active_plugins = get_option( 'active_plugins' );
       array_push($active_plugins, 'cloudflare-flexible-ssl/plugin.php');         
       update_option( 'active_plugins', $active_plugins ); 
   }
add_action( 'init', 'activate_plugin_via_php' );