This can be used in the future for sync so that we can be more
intelligent with what we're doing, and only sync up what's needed
I'd like to eventually replace this with something more like a merkle
tree, hence the hash field I've exposed, but that can come later
Although this does include a much larger number of count queries, it
should also be significantly more cache-able. I'll follow up with that
later, and also follow up with using this for sync :)
* Switch to Cargo workspaces
Breaking things into "client", "server" and "common" makes managing the
codebase much easier!
client - anything running on a user's machine for adding history
server - handles storing/syncing history and running a HTTP server
common - request/response API definitions, common utils, etc
* Update dockerfile
