feature Add support for reordering for belongs_to resources

[delphist]

#3

[yjukaku]

I would love to see this merged. However, I think this might be the better way to go?

reorder_url, query_params = active_admin_resource_for(resource.class).route_instance_path(resource).split '?', 2
reorder_url += "/reorder"
reorder_url += "?" + query_params if query_params
span(reorder_handle_content, :class => 'reorder-handle', 'data-reorder-url' => reorder_url)

[delphist]

@yjukaku need to check it, maybe yes – hard to remember where i'm used it to reproduce the bug. Give me some time, please

[dkniffin]

@delphist Any update on whether @yjukaku's suggestion works? Also, would you mind fixing the conflict with master?

[dkniffin]

@delphist is this still valid? If so, can you please rebase to get the new test suite and fix the conflict?