Adding a .env file

[rzarviv]

I thought about adding a .env (a.k.a dotenv) file to the project. It could be very useful when we want to provide user-specific preference .
for example: if I want to open the browser when a test runs, I should comment the --headless=new arg in fixtures.js, but I need to uncomment it before I create a pull request so it won't affect any other developer's configuration.

I'd like to hear your thoughts about it.

[baruchiro]

For one case I don't think it is needed.

But I agree that commenting out the --headless=new is annoying, you're welcome to think about how to control it easily, from the command line or env var or something.