emulate/traffic: apply new logger to replace print

emulate/traffic: apply new logger to replace print

These print are actually progress infomation, should use logger to
print to stderr, other than stdout.

Signed-off-by: Joe Guo <joeg@catalyst.net.nz>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>