Add click_button helper method to TestAPI

[#69469480]

Special case for iPad (using jQuery).
Make sure that "Oil and Water" tests works on iPad correctly

[#69469480]
Add Capybara API available for test scripts

[#69614706]

Raw Selenium Webdriver API is still available, Capybara usage is
optional.

I did it mainly to test if issues on Mobile devices are somehow
handled (but I can't see any difference).