Changes

One of the previous issues with this python script is that it
suppressed the output of the bash script it was running
(run_scm_all.bash). It is important to see what cases successfully
ran and what cases failed. I have altered the script so that
it doesn't suppress the output of run_scm_all.bash.

Note: the output from the bash script won't be printed to output
until all the cases in run_scm_all.bash have been run to completion.

I am setting the exit_code for the python script to be based on
what is passed out from the bash script for the set of
run_scm_all.bash commands for each flag grouping. It any flag test
fails, the overall exit code from the test will also be set to
a fail result.

I added some helpful print statements and imported "sys" for the
sys.exit statement.

Changing the generalized vertical grid Jenkins test to use the new
run_clubb_w_varying_flags.py python script instead of the traditional
run_scm_all.bash.

When the run_clubb_w_varying_flags.py script is running a generalized
vertical grid test, use a stats file that has a greatly reduced number
of stats. Stats aren't important for this test. We don't want to eat
up too much storage space or waste extra time with stats.