Correct NumCPUs on exclusive jobs

Correct NumCPUs count for jobs with --exclusive option.
bug 909
When creating reservation with CoreCnt check that Slurm
uses SelectType=select/cons_res otherwise don't send the
request to slurmctld and return an error.
Generalize commit 76082c30b4ae04.
Save the state of scheduled node reboots so they will not be
lost should the slurmctld restart.
Add memory test to job_submit/partition plugin