Resolve BMK-244
Implement a 'container_exec' parameter in the YAML configuration to select which container platform (docker/singularity) to use if -d/-s are not passed on the command line (docker by default).
Implement a 'container_exec' parameter in the YAML configuration to select which container platform (docker/singularity) to use if -d/-s are not passed on the command line (docker by default).