normalize return keys for bulk delete and support > 10000 objects
When we ask to delete all objects, actually list them all
If the Response Status is not 200 and Errors is empty, add the Response Body to errors
Add test for 413 to populate errors, when none are returned from the API
Merge pull request #480 from sivel/fix-bulk-upload

BulkDeleter: normalize return keys and support > 10000 objects