Add latest_template(_providers) in dehydrate step to prevent infinite recursion

Originally, these were full tastypie resources, but because latest_template had
a group associated with it, which would try to add its latest template, which
had a group associated with it...and so on.
Removed authnz

It wasn't working quite as planned, and isn't actually needed at this point,
so we can revisit it if/when the need arises.