Include `href` or `to_param` when constructing URLs client side

One nice feature that Rails provides is easy changes to URL generation
(assuming the param starts with the ID). All you have to do is

```ruby
def to_param
  [id, name].to_param
end
```

and everything "Just Works". This is lost, however, if you're manually
constructing URLs on the client side. This is avoided, if as a general
rule of thumb, we let the server decide how to construct the URLs, and
pass that information along.
Should we put the emphasis on "constructing URLs client side" more up front?

I also think it might make sense to give some context, do we do this for everything? Backbone, Angular, even just plain CoffeeScript?

I know this won't really apply to Ember, since Ember-Data takes care of most of this for you anyways.