CppND-Traffic-L1

Tasks finished are in:

• src/TrafficSimulator-L1.cpp: nVehicles (rand number)
• src/Vehicle_Student.cpp: _threads.emplace_back(std::thread(&Vehicle::drive, this)); in Vehicle::simulate()
• src/TrafficObject.cpp:

    for(auto &t : _threads){
      t.join();
    }