sessiontest: Don't bind to 0.0.0.0
Depending on the context 0.0.0.0 might be a non-routeable address, but when binding listening sockets it also means any local addresses. Which is usually not something you want a unit test to bind to on a machine with multiple adresses. Use 192.168.0.2.1 instead from the TEST-NET-1 block described in RFC 5737 [1].