Allow the browser to be open until it's explicitly closed

[davidmles]

Simple description about the feature

As soon as the Ruby script ends, the browser launched by puppeteer-ruby is closed.
This doesn't happen with the JS version, where the browser is open until it's explicitly closed.

Usecase / Motivation

It would be cool to leave the browser open, as it's useful in some cases. For example to solve some human-test challenge manually.

[davidmles]

Never mind. I used a different approach, using the wait_for_function method.