Warn factory operators about RLIMIT_NPROC
In the good old (RHEL5) days, RLIMIT_NPROC was set by the kernel to the number of physical pages / 32, which is relatively high on modern computers.
RHEL6 started shipping /etc/security/limits.d/90-nproc.conf, which set RLIMIT_NPROC to 1024. Great for fork-bomb avoidance, not so great for glideinWMS factory.
We should check this and emit a warning (via resource.getrlimit).
On second thought, RHEL6 sets only a soft limit. Maybe we should check it and bump it up to 10k if it's too low.