Place red/green arrows after number throughout
Improve customer satisfaction responsiveness

Change the previous month font size at the same time as the current
month.
Fix cust. sat. font on small screens

Fix the font size of the previous month number on the customer
satisfaction module so that it stays proportional to the main percentage
number on screens below 640px.
Merge pull request #188 from alphagov/cust-sat-design-tweaks

Customer satisfaction design tweaks