refactor mets scheme

broker/src/asapo_broker/database/mongodb.go

broker/src/asapo_broker/database/mongodb_test.go

common/cpp/include/asapo/database/database.h

common/cpp/include/asapo/unittests/MockDatabase.h

common/cpp/src/database/mongodb_client.cpp

common/cpp/src/database/mongodb_client.h

consumer/api/python/asapo_consumer.pyx.in

examples/consumer/getnext_python/check_linux.sh

examples/consumer/getnext_python/check_windows.bat

tests/automatic/broker/get_meta/check_linux.sh

tests/automatic/broker/get_meta/check_windows.bat

tests/automatic/consumer/consumer_api_python/check_linux.sh

.../automatic/consumer/consumer_api_python/check_windows.bat

tests/automatic/mongo_db/CMakeLists.txt

...atic/mongo_db/insert_retrieve/insert_retrieve_mongodb.cpp

tests/automatic/mongo_db/meta/CMakeLists.txt

tests/automatic/mongo_db/meta/cleanup_linux.sh

tests/automatic/mongo_db/meta/cleanup_windows.bat

tests/automatic/mongo_db/meta/meta_mongodb.cpp