Remove guide list from bottom of phase pages

Analytics shows us that no-one is clicking on them and it's possible that they are
distracting users from the 'Next' links. Suggest we check the analytics in a month
to see if there's been any effect.
Fix up page classes
Restyle phase page navigation
Merge branch 'master' into phases
Merge pull request #158 from alphagov/phases

Phases page update