new: strip trailing white space from generated zar.json
new: strip trailing white space from generated zar.json

The JSON generated by json.dump has lots of trailing white space. We
should not let the user start with such a crufty file.

zerovm/zerovm-cli,zerovm/zerovm-cli,zerovm/zpm,zerovm/zerovm-cli,zerovm/zerovm-cli,zerovm/zpm,zerovm/zerovm-cli,zerovm/zpm,zerovm/zerovm-cli,zerovm/zpm,zerovm/zpm,zerovm/zpm