Only call save if model implements save

Eliminates the need to create a stub save method on a model that
doesn’t use ActiveRecord.

Author: lgebhardt

lib/jsonapi/resource.rb

@@ -51,7 +51,6 @@ def change(callback)
           if @save_needed || is_new?
             deferred = true if save == :deferred
           end
-
         end
       end
 
@@ -123,7 +122,12 @@ def _save
         raise JSONAPI::Exceptions::ValidationErrors.new(@model.errors.messages)
       end
 
-      saved = @model.save
+      if defined? @model.save
+        saved = @model.save
+      else
+        saved = true
+      end
+
       @save_needed = !saved
 
       return :completed

test/fixtures/active_record.rb

@@ -262,10 +262,6 @@ def destroy
     $breed_data.remove(@id)
   end
 
-  def save
-    true
-  end
-
   def valid?
     @errors.clear
     if name.is_a?(String) && name.length > 0