Order submenu broken for custom roles

There are 2 issues with the ability checks on the order submenu when using custom roles:

- Conditions using `&&` are not working as expected (`&&` operator takes precedence over `can?` method call)
- `can?` calls are not following cancan conventions of passing a model instance or class.

These fixes allow a custom ability class like the following to work as expected:

```ruby
module Spree
  class ShopkeeperAbility
    include CanCan::Ability

    def initialize(user)
      user ||= Spree.user_class.new

      if user.respond_to?(:has_spree_role?) && user.has_spree_role?('shopkeeper')
        can :manage, Spree::Order
        can :manage, Spree::Adjustment
        can :manage, Spree::Payment
        can :manage, Spree::ReturnAuthorization
      end

    end
  end
end
```