generateUrl opens browser automatically

[mcamara]

For lazy people (as me), copying and pasting the url is too much hassle. With this small fix, the url is automatically open in user's default browser.

Thanks for the good work!

[toniov]

Thanks for the PR!

A couple of things:

• Maybe it's not a good idea to open the browser without asking first (plus it would be a breaking change). Doing it through an option could be a better idea (something like $ gcal generateUrl -o.

• It needs to be cross-platform, using opn it could be implemented easily.

[mcamara]

You're right, I always forget windows users! I'll fix it later!

[mcamara]

I've made the changes we talked about. What do you think now? 😸

[toniov]

Thanks! Looks good!

Besides the comments, if you add the new option to help.js we are good to go I think!