test and fix #282

Sessions' last use updates weren't getting persisted to the database
because the update statement wasn't passing through the hash.

Also address a TODO of tracing in tests by using the same tracing
setup as in production.

server/base/lib.rs

@@ -7,5 +7,6 @@ mod error;
 pub mod shutdown;
 pub mod strutil;
 pub mod time;
+pub mod tracing_setup;
 
 pub use crate::error::{prettify_failure, Error, ErrorKind, ResultExt};