Avoid a deprecation warning in Rails 4.2

The deprecation is triggered by passing string keys for controller or
action to the url helper.
For what it's worth, you _can_ still pass controller and action to url_for without deprecation, as symbol keys:

     url_for("controller" => "foo", "action" => "bar") #deprecated 
     url_for(:controller => "foo", :action => "bar") # not deprecated

So removing the symbol keys :controller and :action ought not to be related to that deprecation warning. Maybe it was a different deprecation warning?  Because, yeah, in any event, there's no good reason to pass explicit controller and action to a route helper like `catalog_index_url`, perhaps it was a different deprecation warning related to that, and at any rate seems like a good idea. 

But I got worried that url_for had stopped supporting controller and action keys at all, which I rely on sometimes; as far as I can tell it hasn't, it just wants you to pass them as symbols not as strings.