Refactoring of Receiver

common/cpp/include/system_wrappers/io.h

common/cpp/include/system_wrappers/system_io.h

common/cpp/include/unittests/MockIO.h

common/cpp/src/system_io/system_io.cpp

receiver/src/network_producer_peer_impl.h

receiver/src/network_producer_peer_impl_handlers.cpp

receiver/src/receiver.cpp

receiver/src/receiver.h

receiver/unittests/test_network_producer_peer_impl.cpp

receiver/unittests/test_receiver.cpp

tests/system_io/ip_tcp_network/ip_tcp_network.cpp

..._io/ip_tcp_network_speedtest/ip_tcp_network_speedtest.cpp