Handle unprocessed items in batch read/write operations

[Darren]

Until now, we've just been logging unprocessed items - it's time to get around to handling them appropriately -

https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchWriteItem.html

https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchGetItem.html

[Gilad Barkan]

The priority as U see it is for agendas not to include image data.

[Gilad Barkan]

*I (dumb auto-correct)