Explicitly wrap all raw queries in parenthesis

* Prevents potential problems with OR conditions and other operators
  applying to more than just the intended statement

[#915 state:resolved]

lib/dm-core/adapters/data_objects_adapter.rb

@@ -494,7 +494,8 @@ def conditions_statement(conditions, qualify = false)
               comparison_statement(conditions, qualify)
 
             when Array
-              conditions  # handle raw conditions
+              statement, bind_values = conditions  # handle raw conditions
+              [ "(#{statement})", bind_values ]
           end
         end