make styleguide fixed on old browsers

inline with implementation used for main site
Correct naming for files
Merge pull request #342 from moneyadviceservice/bug/styleguide-css

add a fixed and responsive styleguide css file
Add basic components to styleguide
Add basic styling
Remove mini-heading
Add components to static guide
Update markup and css to achieve responsive layout
Change 2 column categories to single columns
Move related links stylesheets to the correct directory
Remove styling from lists
Add unstyled-list to CMS directory
Remove underscores from manifest files
Rename layout element of the hr
typography placeholder for related links
add background colour variable
Add classes to list items in related links, categories
Style related links and categories
Add hr to KSS
Add bottom margin to the related content section