[PLAT-167] Upgrade Rails to 4.1

_"Rails 4.0 has removed attr_accessible and attr_protected feature in favor of Strong Parameters. You can use the Protected Attributes gem for a smooth upgrade path"_(http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html).

Removing the attr_protected is not as simple as it first may seem, so I'm taking the conservative route. We can remove it in another story if we'd like.