config option to cause use of pseudorandom device /dev/urandom

handy in clouds where /dev/random is not connected to a noisy source (which is a lot) and where we don't need super high security

solves a problem where things just seem to halt -- especially where ssh is concerned

a better way is to configure /dev/random to get data from a trusted random source periodically, but that's not universal (whereas this workaround of `ln -s /dev/random /dev/urandom` is universal as far as i've seen!)

even nicer are clouds and images where /dev/random comes configured properly!