Update docker-entrypoint.sh: Fix curl calls in running checks
This forces curl to exit with a non-zero exit code if it receives a 4xx or 5xx HTTP error from the server it connected to.
Also, this enhances the fedora_running check to use value of $FCREPO_PATH from the env file in the same way as it is used throughout the rest of RDMS/ReSeeD.
We have tested this change on our development instance of RDMS/ReSeeD.