Cron-scripts enhancements

[cbegeman]

I noticed the following attributes while testing #641, presumably not specific to aurora, which we may want to change:

1. It assumes you are running launch_all.sh from $POLARIS_ROOT. When I ran it from cron-scripts, I got /home/cbegeman/polaris-worktree/add-cron-aurora/cron-scripts/tasks/polaris_cdash/launch_polaris_ctest.sh: line 58: ./deploy.py: No such file or directory
2. I needed to set POLARIS_ROOT manually before running launch_all.sh. I didn't see any place in the code where this was supposed to be set. CMake Error: The source directory "/e3sm_submodules/Omega/components/omega" does not exist.

   polaris/cron-scripts/tasks/polaris_cdash/launch_polaris_ctest.sh

   Line 10 in 2a4edc6

   OMEGA_HOME="${POLARIS_ROOT}/e3sm_submodules/Omega"

3. I needed to have run git submodule update --init e3sm_submodules/Omega in POLARIS_ROOT. It would be great if this were automated.