Auto-save on timeout

[cooperlab]

@nalisnik Initiate a save event before timing out a session so that users may resume training.

[nalisnik]

I've added the auto-save routine and the session manager will call it when timing out. Need to determine how to keep track of the auto-save datasets. Typically when the user finalizes a session, the dataset is saved to an HDF5 file and the database is updated with the metadata for the dataset. The learning server does not interface with the database so it is not a trivial task. I'll come up with a few ways to handle updating the database before moving forward.