Allow authorize_actions_for to pass options

This change simply splats the result of the method called to get the
resource to authorize in a controller (as a result of using the
.authorize_actions_for class method).

This will have no effect on existing calls, since the .authorize_actions_for
previously supported only a resource method that returns a single value.

This change will allow someone to return an array in their resource
method, including both the resource to authorize and options.  This can
be very helpful for authorizing create actions.

For example:

class WibblesController
  before_filter :load_foo
  authorize_actions_for :foo_wibbles, only: :create

  ...

  private

  def foo_wibbles
    [Wibble, { foo_id: @foo }]
  end
end