start updating producer

common/cpp/include/common/networking.h

common/cpp/include/database/database.h

common/cpp/include/unittests/MockDatabase.h

common/cpp/src/database/mongodb_client.cpp

common/cpp/src/database/mongodb_client.h

receiver/src/request.cpp

receiver/src/request.h

receiver/src/request_factory.cpp

receiver/src/request_handler_db_write.cpp

receiver/unittests/receiver_mocking.h

receiver/unittests/test_request_factory.cpp

receiver/unittests/test_request_handler_db_writer.cpp