added cache_only mode, tests

common/cpp/include/asapo/common/data_structs.h

common/cpp/src/data_structs/data_structs.cpp

common/cpp/unittests/data_structs/test_data_structs.cpp

consumer/api/c/include/asapo/consumer_c.h

consumer/api/cpp/include/asapo/consumer/consumer_error.h

consumer/api/cpp/src/consumer_c_glue.cpp

consumer/api/cpp/src/consumer_impl.cpp

consumer/api/cpp/unittests/test_consumer_impl.cpp

consumer/api/python/asapo_consumer.pxd

consumer/api/python/asapo_consumer.pyx.in

producer/api/python/asapo_producer.pxd

producer/api/python/asapo_producer.pyx.in

receiver/src/request.cpp

receiver/src/request.h

receiver/src/request_handler/request_handler_db_write.cpp

receiver/unittests/receiver_mocking.h

...ttests/request_handler/test_request_handler_db_writer.cpp

tests/automatic/full_chain/CMakeLists.txt

.../full_chain/simple_chain_cache_only_python/CMakeLists.txt

.../full_chain/simple_chain_cache_only_python/check_linux.sh