Merge pull request #1176 from lgebhardt/use_destroy_vs_delete_v0.9

Use `destroy` instead of `delete` to ensure callbacks are called

Author: lgebhardt

lib/jsonapi/resource.rb

@@ -352,7 +352,7 @@ def _remove_to_many_link(relationship_type, key, options)
 
         @reload_needed = true
       else
-        @model.public_send(relationship.relation_name(context: @context)).delete(key)
+        @model.public_send(relationship.relation_name(context: @context)).destroy(key)
       end
 
       :completed