Fix has_any_role? to work with unsaved records.

`has_any_role?` doesn't work with unsaved records, while `has_role?` does. Here's the current behaviour:

    >> u = User.new
    => #<User id: nil, [...]>
    >> u.add_role :administrator
    => #<Role id: 417269330, name: "administrator", [...]>
    >> u.has_role? :administrator
    => true
    >> u.has_any_role? :administrator
    => false

This patch fixes the issue so that in the above example `has_any_role?` would return true.