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.
json: use packet timestamp if available

This patch updates the JSON output plugin to have it use the
timestamp of the packet if available. The date format used
for the timestamp is now using ISO 8601 to have an easy
import in most software (tested with logstash and splunk).

Signed-off-by: Eric Leblond <eric@regit.org>
printpkt: oob.time.sec was not used

This patch supresses the oob.time.sec from the input keys as this
is not used when creating the string corresponding to the packet.

Signed-off-by: Eric Leblond <eric@regit.org>
ulogd: fix loglevel handling

It was always default if not specified by command parameter.

Signed-off-by: Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>