Optional route path when used with query params

With ember `{{link-to}}`, the route path can be omitted when used in conjunction with query params.

```
{{#link-to (query-params foo="bar")}}Baz{{/link-to}}
{{link-to "Baz" (query-params foo="bar")}}
```

I do this all the time in a project but ran into issues when trying to convert some of them to the `{{href-to}}` format.
