Keep the text of the notification emails in whitelabel#169

Keep the text of the notification emails in whitelabel therefore without references to uptimerobot and therefore for example without the need to validate the emails otherwise always validate it in whitelabel for example with my sender email

Hi @Giovanni Giliberti . Please, can you specify your usecase? Do you sent downtime email notifications directly to your customers? Wouldn’t it be better to send them reports? -> https://uptimerobot.nolt.io/11