seed the random number generator befor using it avoids always generating the
same "random" number.
fix always choosing the last server when many given
Using crypto/rand and draining the system entropy pool is probably overkill here. We really just need a "rand.Seed(time.Now().UnixNano())" once at startup time.
@dgryski Yeah I like this more as well. Implemented in #28.
done in #28