Fix firmware version - call port.open() before querying it

[alexrudd2]

Closes #124 ... mostly.

The CLI will still throw an error (throw new Error("TODO")), but it will at least print the firmware version before doing so.

❯ npx . --firmware-version
EBBv13_and_above EB Firmware Version 2.8.1
/Users/a.ruddick/Documents/github/saxi/dist/server/ebb.js:73
            throw new Error("TODO");

[andypiper]

Working as described above, for me. 👍🏻