Prefer subquery over materialising list of roles (#559)

Signed-off-by: Thomas McDonald <tom@conceptcoding.co.uk>

Co-authored-by: Rafael Chiarello <rafael.cote@gmail.com>

lib/rolify/adapters/active_record/resource_adapter.rb

@@ -26,7 +26,7 @@ def resources_find(roles_table, relation, role_name)
       end
 
       def in(relation, user, role_names)
-        roles = user.roles.where(:name => role_names).select("#{quote_table(role_class.table_name)}.#{quote_column(role_class.primary_key)}").to_a
+        roles = user.roles.where(:name => role_names).select("#{quote_table(role_class.table_name)}.#{quote_column(role_class.primary_key)}")
         relation.where("#{quote_table(role_class.table_name)}.#{quote_column(role_class.primary_key)} IN (?) AND ((#{quote_table(role_class.table_name)}.resource_id = #{quote_table(relation.table_name)}.#{quote_column(relation.primary_key)}) OR (#{quote_table(role_class.table_name)}.resource_id IS NULL))", roles)
       end