Removes scala.concurrent.impl.Future.apply and replaces it with s.c.Future.unit.map(_ => body)
Makes the System Property 'scala.concurrent.context.maxThreads' cap the max number of threads spawned.
This is important since Managed Blocking for ForkJoinPool otherwise risks spawning too many threads and
crash the JVM. The default is "1x" the number of processors on the machine, the question is if this is a
good default, but at least it hasn't changed in this commit.