Vigiles CLI does not exit with non-zero exit status on errors

[tchernobog]

We use the vigiles-cli in CI/CD, and it is difficult to have jobs blocking on it because it always return a zero exit status even when it fails e.g. due to a server error 500, or a 404, or 403, etc.

It would be good if such HTTP errors would be somehow propagated so the application exits with a different return code.

I think here:

 except Exception as err:
        print(err)

can simply be changed to call exit(1) after printing. It would also be appreciated if errors could go to stderr instead of stdout.