use different session identifier and stuff

Use PG in development and fixes crashes

As stated in chat, this is what the issue was. While attempting to debug it a few days ago we weren't getting any analytics into the issue whatsoever (no stack traces, etc). After a recent attempt to deploy in the staging environment, it was revealed that steam uids are bigints, so this fixes the column definitions for uids to be bigint in postgres.

This does add a development dependency in that you'll need to have postgres running, but it should reduce these kinds of DB issues, which often get missed.
Just curious: why a btree?