Restrict access to the zmq certificates folder.
Set the standalone value for BaseConfig.
Merge remote-tracking branch 'refs/remotes/ivan/bug/set-standalone-flags-for-baseconfig' into develop
Merge remote-tracking branch 'refs/remotes/ivan/feature/restrict-certificates-permissions' into develop
Merge remote-tracking branch 'refs/remotes/ivan/feature/add-backend-alive-check' into develop
Add frontend alive check to the backend.

Stop the backend if the frontend process does not exist any more and
backend is not a daemon.