BidsAppHandler tasks, in setup(), to check if Singularity is configured

[prioux]

A BidsAppHandler task runs its cluster jobs using bosh; it is an error for the sysadmin to configure the associated ToolConfig to have singularity (or docker) container information, because bosh will do the container prep work.

During the setup() step, invoke the ClusterTask methods use_singularity? and user_docker? if if any of them return true, print an error message in the task's log and fail the setup steps: the sysadmin made the config error.