Securerandom: only use random bytes, not extra Stringlib/securerandom.rb...

...inspect output

In our migration from Ruby 1.8 to 1.9 we added a monkey patch to identify places we were using an implicit Array#to_s for concatenating all the elements.  This item popped up.  I don't believe that the existing implementation breaks anything, however I'm confident this was the intent of the author

# Monkey Patch
```ruby
class Array
  def to_s
    raise "check me"
  end
end
```