Allow spawning VMs in different regions #16
Description
Right now all VMs are created in us-west-2 -- it would be nice to also offer a couple other regions as options.
It shouldn't be too hard, spawner.py is virtually ready.
On the OOO side, the AWS user / role will need to be expanded to allow some of the regions we're not using for the games.
We'd also record the user's preference in UserSettings: default_region is already there for this, and ideally geo-locate by default to suggest a good default.