Move data store to backend container

[mbtown01]

Currently, we're using postgres locally on the RPi to store data. This was already a fairly heavy solution, but if we want FROSTI to be as rugged as possible, frequent use of the local SD card as the backing store for Postgres is a weak spot.

If we can cache updates locally and then push data to Azure at some frequency, it would essentially eliminate the need for the local SD card to be anything but readonly.

Need to talk w/ some cloud folks on the right first steps here. A cloud-based DB with an API frontend may be ideal, but I'm sure there are lots of other ways.