Sample function will never pick the last item

See http://play.golang.org/p/BIh-FL_CUH (runs better locally though, playground seems to always return the same results)

Intn(x) will return a number that is from 0 to n-1. In `main.go`, when running the program, Hicham is never picked when doing `ArrayList.Sample()`.
Merge pull request #3 from wari/patch-1

Sample() function will never pick the last item