ulogd: avoid potential double print of message

In case there is no logfile, ulogd could possibly display each
log message twice to stderr.
ulogd: add carriage return as separator

If the file is in DOS mode, the string coming from config file
parsing are containing the carriage return. The result is that
string are not correct and the parsing of confuguration file
is failling.
nfct: use start timestamp if provided

When hash table is not used, the start timestamp was not used even
if the kernel is sending it. This patch modifies the code to use it
when available. This allows to log connection with start and end
with a single message per connection and without the cost of
maintaining the hash table.