This patch changes the default worker count from ::processorcount to the
new ::os_workers fact. ::os_workers is based on the number of processors
(currently cpu/4) but is capped at a maximum of 8 worker processors.
This is a much more reasonable default in general and prevents excessive
resource consumption on systems with a large number of CPUs.
Change-Id: I159bb64d024c2207526c73212d68230d8362164c
4fcd49b592