First pass at an Azure table storage implementation of the deletion operation
Change the 'upper set' test so that it doesn't try to delete a key that doesn't exist
Try catching 404s like with the non-aggregated deletions. Unfortunately this doesn't work as it seems the entire batch is aborted when a record is missing :-/
Remove code to ignore 404s as it just hides the error. Also tried inserting empty entities but Azure doesn't like that if they're part of the same batch
Stop Azure from 404ing on keys that are not in the database by inserting records and then immediately deleting them (this is crazy but it seems to be the only thing you can do that doesn't involve slowly querying each record individually)