Add features to Fruit Jam library

Hello,

Would it be possible to add these features for Fruit Jam's library?

fruitjam.ping,
fruitjam.firmware_version,
fruitjam.MAC_address

Thanks,
Bruce

Start by locating the Fruit Jam library entry point and reviewing its existing public API; the issue names no files, tests, or expected behavior. Clarify how fruitjam.ping, fruitjam.firmware_version, and fruitjam.MAC_address should behave, then verify the completed additions against the library's existing test process.

Written by the indexing model from the issue text.