add an overload of the computeDescendKey method in NodeKey class, in which the keyLabel is a default value.
add an overload of the computeDescendKey method in NodeKey class,
in which the keyLabel is a default value.

ebollens/ccnmp,cawka/ndnx,svartika/ccnx,svartika/ccnx,svartika/ccnx,cawka/ndnx,svartika/ccnx,svartika/ccnx,svartika/ccnx,cawka/ndnx,ebollens/ccnmp,svartika/ccnx,cawka/ndnx,cawka/ndnx,ebollens/ccnmp,ebollens/ccnmp