WIP: fix pedantic errors

CMakeLists.txt

include/caosdb/configuration.h

include/caosdb/connection.h

include/caosdb/utility.h

include/ccaosdb.h

src/caosdb/authentication.cpp

src/caosdb/configuration.cpp

src/caosdb/connection.cpp

src/ccaosdb.cpp

test/CMakeLists.txt

...t_broken_caosdb_client_certificate_file_non_existent.json

test/test_data/test_caosdb_client.json