Rewrite notifications to work without observers

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix email urls, more clear form message

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix notification for success builds

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>