buildbox-casd --version doesn't work

I looked into this today in order to solve BuildStream's need to verify the required version of BuildBox at startup.

I have a few issues here:

• I am unable to find where the latest builds of buildbox are located
  • BuildStream's documentation currently only links specifically to BuildBox 0.0.38 which I presume is probably quite old.
• BuildBox 0.0.38 supports the --version option according to --help, but bails out with this error if given the --version option:

  [buildboxcommon_commandline.cpp:414]: parse error: required positional argument(s) missing from command line

• The version I happen to have installed on my machine is more recent, I think @juergbi gave me the link to the new version after fixing an issue early this year, I'm not sure what version it is, but the result of typing ./buildbox-casd --version yields the following results:

  tristan@pony:~$ buildbox-casd --version
  buildbox-casd unknown

If this is already fixed in more recent versions, please go ahead and close this (and let me know where I can go to find the latest binaries).