Fix: Misc last fixes.

+ livestatus showheader rule for 'json' or 'python' is different than one of 'csv' format.
  breaked a test: test_check_hint_hosts_by_host

+ separators are encoded as their ord() values in the request.
  Need to chr(int(..)) them.

+ Fix: CSV needs to quotes fields if they contain the field separator.
  Use csv lib to encore each row separatedly.