Use example values instead of default during install, var renmaing

scripts/install

@@ -14,14 +14,14 @@ api_secret="$(ynh_string_random --length=32)"
 app_key="$(ynh_string_random --length=32)"
 phantomjs_key="$(ynh_string_random --length=32)"
 
-mail_address=$(ynh_app_setting_get --key=mail_address)
-mail_name=$(ynh_app_setting_get --key=mail_name)
+mail_address=$(ynh_app_setting_get --key=default_from_email_address)
+mail_name=$(ynh_app_setting_get --key=default_from_email_name)
 
 ynh_app_setting_set --key=api_secret --value=$api_secret
 ynh_app_setting_set --key=app_key --value=$app_key
 ynh_app_setting_set --key=phantomjs_key --value=$phantomjs_key
-ynh_app_setting_set --key=mail_address --value="$mail_address"
-ynh_app_setting_set --key=mail_name --value="$mail_name"
+ynh_app_setting_set --key=default_from_email_address --value="$mail_address"
+ynh_app_setting_set --key=default_from_email_name --value="$mail_name"
 
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE

scripts/upgrade

@@ -12,13 +12,13 @@ source /usr/share/yunohost/helpers
 ynh_script_progression "Ensuring downward compatibility..."
 
 if [ -z "${mail_address:-}" ]; then
-	mail_address="true"
-	ynh_app_setting_set --key=mail_address --value=$mail_address
+	mail_address="${app}@${domain}"
+	ynh_app_setting_set --key=default_from_email_address --value=$mail_address
 fi
 
 if [ -z "${mail_name:-}" ]; then
-	mail_name="true"
-	ynh_app_setting_set --key=mail_name --value=$mail_name
+	mail_name="${app}@${domain}"
+	ynh_app_setting_set --key=default_from_email_name --value=$mail_name
 fi
 
 # Delete deprecated `firstname`/`lastname` settings. See upstream https://github.com/YunoHost/yunohost/pull/1516