start working at requests

common/cpp/include/common/networking.h

common/cpp/include/io/io.h

common/cpp/src/system_io/system_io.cpp

producer/api/CMakeLists.txt

producer/api/include/producer/producer.h

producer/api/include/producer/producer_error.h

producer/api/src/producer_impl.cpp

producer/api/src/receivers_status.cpp

producer/api/src/receivers_status.h

producer/api/src/request.cpp

producer/api/src/request.h

producer/api/src/request_pool.cpp

producer/api/src/request_pool.h

producer/api/unittests/test_producer_impl.cpp

producer/api/unittests/test_request.cpp