auto_firmware_version.py not safe/reliable

[dkerr64]

The auto_firmware_version.py script is not safe way to establish the version. The script presumes that git describe --tags will work, but that requires that the git repository actually have tags. Without it you get:

fatal: No names found, cannot describe anything.

And the firmware version embedded into the source is empty. This matters because anyone who forks the repository will not carry over all the tags, each repository have their own tag history.

A better place to pull the version number from would be manifest.json file. This contains the actual version number and is independent of any git tagging.