Add time to log output. Change dafault output path.

Add time to log for more convenient info. Log
to /tmp/nscav2.<timestamp>.log instead of stdout.

Signed-off-by: Krzysztof Opasiak <ups100@tlen.pl>
Adjust nscav2 to work as unix daemon.

Add fork and other required functionality. Add SIGINT signal service
to close all socket and files properly. Daemon makes chdir to / so
awoid usage of relative paths. To klose daemon use:

kill -s SIGINT <PID>

Now some default path are used:

/usr/local/nscav2 - main directory
/usr/loacl/nscav2/etc - default directory for config file
/usr/local/nscav2/crypto - directory where keys are stored by default
/usr/local/nscav2/var/buf - default directory for round robin buffers

Signed-off-by: Krzysztof Opasiak <ups100@tlen.pl>