Pull request: GSoC'13 Wiselib NS-3 Port -- Add all NS-3 port codes into apps/ns3_apps/

This pull request adds all NS-3 port codes into apps/ns3_apps/ folder. When the Wiselib users run 'make ns3' command in generic_apps/, those NS-3 port codes will be automatically copied into NS-3 src folder. By this way, the Wiselib users do not need to modify any codes in NS-3.