packages: add tstat

Tstat is a passive sniffer able to provide several insight on the
traffic patterns at both the network and the transport levels.

http://tstat.tlc.polito.it

Signed-off-by: Tivadar Szemethy <tivadar.szemethy@netvisor.hu>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/packages@37196 3c298f89-4303-0410-b956-a3cf2f4a3e73