LIGHT-138, LIGHT-141. Due to some issues in sending/receiving parts of lnd,
messages with zero length are not sent. So added some mock content to
NeighborAck. Moved sender/receiver from routing message to wrap message
which contains lnwire routing message.
LIGHT-133, LIGHT-138 Make output of `lncli showrouting table` in
two different formats: table and json.
Instead of sending serialized routing table send list of channels.