Summary: Securely seed go's random number generator

Description:
Boiler-plate to securely seed Go's random
number generator (if possible). This library isn't anything fancy, it's just a
canonical way of seeding Go's random number generator. Cribbed from Nomad before
it was moved into Consul and made into a helper function, and now further
modularized to be a super lightweight and reusable library.

Maintainer: pterjan