unsubscribe button stays top right instead of wrapping around, adds small 'x' icon, switches to only 'x' icon on smaller screens
Merge branch 'improve-sub-wrap' of https://github.com/lukesampson/publicwhip into lukesampson-improve-sub-wrap
revert source order to link first and adjust layout css
Did this so that the link to the policy, which give the neccessary context to the button, comes first for screenreader/keyboard users when tabbing through.
swap to 'small screens up' implementation for icon change
This is consistent with the responsive implementation across the app, and importantly keeps the unsubscribe text available to screenreaders at all times.

This commit also removes the icon on wider screens, because the text surfices here.
reduce size of unsubscribe cross
add vertical-align back to icon so it sits top right
Merge branch 'lukesampson-improve-sub-wrap'