Moved `selenium-webdriver` module from dependencies to devDependencies

`selenium-webdriver` is not a direct dependency of `wrowseler`; it is
tool that deals with it receiving an instance of `selenium-webdriver`.

Obviously, `selenium-webdriver` is required by tests
Removed `runflows/index.js`, it isn't needed anymore

I've removed `runflows/index.js`, after folder structured changed it isn't
needed