Added a new append function to nnn-address.h
Added a new append function to nnn-address.h

Used when sending stuff through the wire. It was easier to implement than to
change the existing code.

PhilipsIII/ndn-mobility,PhilipsIII/ndn-mobility,shinrs20/ndn-mobility,PhilipsIII/ndn-mobility,samqixin/ndn-mobility,samqixin/ndn-mobility,shinrs20/ndn-mobility,PhilipsIII/ndn-mobility,samqixin/ndn-mobility,shinrs20/ndn-mobility,shinrs20/ndn-mobility,samqixin/ndn-mobility,PhilipsIII/ndn-mobility,shinrs20/ndn-mobility