Added network request handlers

common/cpp/CMakeLists.txt

common/cpp/include/common/networking.h

common/cpp/include/common/os.h

common/cpp/include/system_wrappers/has_io.h

common/cpp/include/system_wrappers/io.h

common/cpp/include/system_wrappers/io_utils.h

common/cpp/include/system_wrappers/system_io.h

common/cpp/src/has_io.cpp

common/cpp/src/io_utils.cpp

common/cpp/src/system_io.cpp

producer/api/include/producer/producer.h

producer/api/src/producer_impl.cpp

producer/api/src/producer_impl.h

producer/dummy-event-detector-cpp/src/dummy_detector.cpp

receiver/CMakeLists.txt

receiver/src/network_producer_peer.cpp

receiver/src/network_producer_peer.h

receiver/src/network_producer_peer_handlers.cpp

receiver/src/receiver.cpp

receiver/src/receiver.h