Execute browser testing

[x] Chrome Version 57.0.2987.133 (64-bit) on OS X 10.10.5
[x] Opera 43.0.2442.1165 on OS X 10.10.5
[x] Firefox 49.0.2 on OS X 10.10.5
[x] Safari 10.1 on OS X 10.10.5
[x] IE9 (should show unsupported message) BrowserStack
[x] IE10 (should show unsupported message) BrowserStack
[x] IE11 on Windows 8.1 BrowserStack
[x] Edge 14 on Windows 10 BrowserStack
[x] Safari 8 on Yosemite BrowserStack FAIL: Layout breaks -> Fixed with autoprefixer config change
[x] Safari on iOS 8 iPad 2 FAIL: Layout breaks -> Fixed with autoprefixer config change
[x] Safari on iOS 8 iPad Mini 3 FAIL: Layout breaks -> Fixed with autoprefixer config change
[x] Safari on iOS 9.3 iPad Mini 4 FAIL: Credit card number validation fails sometimes but layout works -> Fixed with Stripe v3 JS lib update (Elements)
[x] Safari 9.1 on El Capitan BrowserStack FAIL: Credit card number validation fails sometimes -> Fixed with Stripe v3 JS lib update (Elements)
[x] Android 4.4 Chrome on Samsung Galaxy S5
[x] Safari on iOS 10.1.1 iPhone 6

Test sequence:

alvarcarto / alvarcarto-designer