Fixed SPF record to ba handled the same way as TXT record

- strings are quoted

Fixed checking the TXT/SPF record value size

- Record size can be bigger than 255 characters but in that
  case it needs to be split into more smaller parts
  e.g., "a" "b" "c" instead of "a b c"
- The old implementation expected the value size to be max 255
  in total, which was wrong

Deleted file added by backporting a patch