Make token optional?

[rshade]

Original issue: flexera-public#46

I think forcing token be required and at least 16 chars is inconvenient to use, because I'd like to use it as a ngrok replacement. This commit maple3142@57be221 is my attempt, which works without token. However, I am not familiar with golang, so I am not sure if this is correct (Doesn't introduce new bug on other features).