Header fixes

Pull request to get header looking as per design

Includes functionality to push down the header past the MAS logo after a couple of seconds after loading on mobile
This can be done for you using the `uiEvents` variable. For example: https://github.com/moneyadviceservice/dough/blob/master/assets/js/components/Validation.js#L26-L31

It just means that event listeners are called out at the top of each component for consistency