Remove the assumption that you wanted a full-refresh if nothing was supplied

I was trying to be smart and if:

- refresh-on-success
- refresh-on-error
- refresh-on-error-except 

none of these provided, then we would attempt a full refresh.  This fails in the following scenario:

1.  Delete a resource using tg-remote
2.  Haven't specified any refresh keys cause there's nothing to refresh
3.  Your action does a `redirect_to` the index page, and your XHR follows it
4.  This code gets triggered by mistake:
```coffeescript
    else if @opts.fullRefresh
      Page.refresh()
```
and this attempts to re-GET the current resource, but the current resource no longer exists because you just deleted it

I think the smarter thing to do is, if you want a `full-refresh`, actually supply the attribute

cc @celsodantas @tylermercier @nsimmons @kurtfunai