Improve how ruby features are required

* Don't require bcrypt explicitly (done by bundler);
* Regroup require calls in application configuration.

app/models/sound.rb

@@ -1,5 +1,3 @@
-require 'fileutils'
-
 class Sound < ActiveRecord::Base
   belongs_to :track
 

app/models/user.rb

@@ -1,5 +1,3 @@
-require 'bcrypt'
-
 class User < ActiveRecord::Base
   include BCrypt
 

config/application.rb

@@ -12,6 +12,8 @@ require 'action_view/railtie'
 # you've limited to :test, :development, or :production.
 Bundler.require(*Rails.groups)
 
+require 'fileutils'
+
 module Scube
   class Application < Rails::Application
     # Settings in config/environments/* take precedence over those specified here.

spec/support/decrease_bcrypt_cost_factor.rb

@@ -1,5 +1,3 @@
-require 'bcrypt'
-
 module BCrypt
   class Engine
     remove_const  :DEFAULT_COST