Use more reliable way instead of "$I->wait(7)"

[ceckoslab]

Hello @Zifius

I noticed that in the bottom of CheckoutCest::testOnePageCheckout() you are using $I->wait(7) after the "Place Order" button is pressed. I don't think that this is the most reliable way, because the waiting time may vary depending on many factors.

Do you think that more reliable solution can be used?

[ceckoslab]

Hello @Zifius ,

I think that the function "waitForJS" may come handy - http://codeception.com/docs/modules/WebDriver#waitForJS

[Zifius]

Hello @ceckoslab, looks like this is what we need. Can you send a PR please?