Fix logging with --no-colors outputting objects

The issue here was that when logging from Attester with `--no-colors`
passed in command line, it sometimes logged the String object (console.dir
fashion) instead of a logging a string literal (precisely it was fixed by
https://github.com/Marak/colors.js/commit/5ca667df4a9f86f6c202eca5eb1524cd8d2dd331).

Close #48.