Removing method calls to methods that don't always exist

- first_source isn't always available
- Models are dataset and have a #model and #first_source but a dataset
  isn't necessarily a model, so it will not always respond to those
method calls.

lib/new_relic/agent/instrumentation/sequel.rb

@@ -49,10 +49,10 @@
     # Sequel's Dataset instance methods
     ::Sequel::Dataset.class_eval do
 
-      add_method_tracer :execute,        'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : "Dataset#{self.first_source}"}/find'
-      add_method_tracer :execute_insert, 'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : "Dataset#{self.first_source}"}/create'
-      add_method_tracer :execute_dui,    'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : "Dataset#{self.first_source}"}/update'
-      add_method_tracer :execute_ddl,    'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : "Dataset#{self.first_source}"}/all'
+      add_method_tracer :execute,        'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : self.sql}/find'
+      add_method_tracer :execute_insert, 'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : self.sql}/create'
+      add_method_tracer :execute_dui,    'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : self.sql}/update'
+      add_method_tracer :execute_ddl,    'ActiveRecord/#{self.respond_to?(:model) ? self.model.name : self.sql}/all'
 
     end