Use id property as id attribute rather than resource_uri

Hi Paul,

I was working through this tutorial using backbone-tastypie but ran into issues because the URLs generated to display details views used the id attribute values but the resource_uri attribute of the models was used when they were added to the collection. So, when I would try to get a model out of the collection by the id, it would return undefined.

I'm not sure if I ran into this because I'm doing something incorrectly, but I forked the code to change it such that the resource_uri attribute isn't used as the id.  This is a backwards incompatible change so if you think it's worth including, I could add some way to configure it.

Thanks,
Meetesh