Divide by zero：ConsumerCbr's Frequency maybe set zero,and cause bug!!!

[fgfxf]

the consumer 's interest packet's frequency is a double varble,and can be set to zero.

ndnSIM/apps/ndn-consumer-cbr.cpp

col 93:
m_sendEvent = Simulator::Schedule((m_random == 0) ? Seconds(1.0 / m_frequency)
: Seconds(m_random->GetValue()),
&Consumer::SendPacket, this);

SetAttribute("Frequency", ns3::StringValue("0"));

i want to set Frequency small to make frequency little.

SetAttribute("Frequency", ns3::StringValue("0.1")); // 10 second a interests