Need to be able to attach data to a batch after creating the batch

[gcpoole]

Batches should be created with no data. Then add data to a batch. When data are committed, the batch and the data should be archived within the folder according to a load date.

In order for this to work, data should be saved as a dataframe in the batch folder separately from the batch.

[gcpoole]

Decided this was a bad idea... Could compromise the history of a batch...