Add support for gcc7 C++17, minor fixes to support it and modification in...

.gitlab-ci.yml

CMakeLists.txt

ReleaseNotes.md

catalogue/CMakeLists.txt

cmdline/CMakeLists.txt

cmdline/restore_files/CMakeLists.txt

common/CMakeLists.txt

common/exception/CMakeLists.txt

continuousintegration/orchestration/tests/CMakeLists.txt

cta-release/CMakeLists.txt

cta.spec.in

disk/CMakeLists.txt

eos_cta/CMakeLists.txt

eos_grpc_client/CMakeLists.txt

mediachanger/CMakeLists.txt

mediachanger/castorrmc/CMakeLists.txt

mediachanger/castorrmc/common/CMakeLists.txt

mediachanger/castorrmc/rmc/CMakeLists.txt

objectstore/CMakeLists.txt

python/CMakeLists.txt