refactor, add integration tests

common/cpp/include/common/data_structs.h

consumer/api/cpp/include/consumer/data_broker.h

consumer/api/cpp/src/server_data_broker.cpp

consumer/api/cpp/src/server_data_broker.h

consumer/api/cpp/unittests/test_server_broker.cpp

consumer/api/python/asapo_consumer.pxd

consumer/api/python/asapo_consumer.pyx.in

tests/automatic/consumer/consumer_api/consumer_api.cpp

tests/automatic/consumer/consumer_api_python/consumer_api.py