Fixes to enable mpirun to work again on Cray

The ess pmi module was not handling aprun launched
daemons.  All daemons were thinking they were vpid 1.

Also, turns out that on cray systems using MOM nodes
for launched jobs, just detecting whether or not a
process is in a PAGG container is not sufficient.

Crank up the priority of the alps PLM component in the
event that the configure detected the presence of both
slurm and alps.

Have the ESS pmi component open the pmix framework and
select a pmix component.