FIX #152 force write image ID

ManyManyList::add did not call write on dataObject, so the image was never attached

src/BulkUploader/BulkUploadHandler.php

@@ -93,6 +93,7 @@ class BulkUploadHandler extends RequestHandler
 
         $fileRelationName = $this->component->getFileRelationName($this->gridField);
         $record->{"{$fileRelationName}ID"} = $fileID;
+        $record->write(); //HasManyList call write on record but not ManyManyList, so we call it here again
         
         $this->gridField->list->add($record);