Make User and Session no longer Squeryl-reliant.

This itched. Lots.

The next thing to do: make auth use Slick instead of Squeryl. This will
make our request _much_ faster. However, it's not a trivial change and
this isn't my actual job today; let's wait until I'm struck by another
flash of inspired coding.
Nix NaN nDocuments in VizTabs popup

We don't know the number of documents in a DocumentSetCreationJob, so we
can't display it. [resolves #77112978]