Several things:

* Fixed an important bug recently introduced in fmin
  namely: (2 * 31 - 1 != 2 ** 31 - 1)

* Removed the rng from Bandit and Domain. They're supposed to describe
  a search space, they don't need a random number state. It was confusing.

* Simplified rand.py to not use Bandit.rng

* Modified Domain.evaluate to require a status key from returned dictionaries.
  The loss is only checked if status == 'ok'.  That's the behaviour that was
  documented, and it seems more reasonable then it what it used to be doing.
removed some commented code