Fix setting environment without usage RAILS_ENV

Running

    rails s -e production

or

    rails c production

didn't work correctly: the environment was still set still on
development. The reason was, that `lib/util/password.rb` was loaded
form `lib/katello_config.rb` before Rails environment was initialized.
Because in password.rb load phase, `Rails.env` was called, it set the
environment before the `-e` option was processed.

Setting the rounds value in `config/environments/test.rb` probably
makes more sense, leaving the `util/password.rb` file independent from
knowing anything about Rails env.