Fix count-facts

You don't have to change this because that will work, but there are heaps easier ways to get unique numbers (because I think you only need unique not random right?). Depending on what you need there are two techniques with different properties:
 - Guaranteed uniqueness while your process is running: `$$`
 - Global uniqueness `date '+%Y%m%d%H%M%S'-$$`

Both are portable and also have stronger guarantees of uniqueness than take a chunk from urandom.

Not important, just handy if you need it in future. /cc @raronson @charleso