Added ApexClass and Attachment to the CurrencyIsoCode Override

Added ApexClass and Attachment to the CurrencyIsoCode Override.  These classes do not have CurrencyIsoCode field

Author: ImJohnMDaniel

fflib/src/classes/fflib_SObjectSelector.cls

@@ -33,7 +33,9 @@ public abstract with sharing class fflib_SObjectSelector
     /**
      * This overrides the Multi Currency handling, preventing it from injecting the CurrencyIsoCode fie ld for certain System objects that don't ever support it
      **/
-    private static Set<String> STANDARD_WITHOUT_CURRENCYISO = new Set<String> { 'AsyncApexJob' };
+    private static Set<String> STANDARD_WITHOUT_CURRENCYISO = new Set<String> { AsyncApexJob.SObjectType.getDescribe().getName()
+                                                                                , ApexClass.SObjectType.getDescribe().getName()
+                                                                                , Attachment.SObjectType.getDescribe().getName()  };
 
     /**
      * Should this selector automatically include the FieldSet fields when building queries?
@@ -391,4 +393,4 @@ public abstract with sharing class fflib_SObjectSelector
 
         return queryFactory;    
     }    
-}
+}