Puts optimizely behind a feature switch.
Corrects readme info about feature detection.
Merge pull request #461 from moneyadviceservice/f/optimizely-toggle

Puts optimizely behind a feature switch.
Give non-navigation categories a "Home" breadcrumb
Add feature coverage for non-navgational category breadcrumbs
Add cassettes for non-navigational category breadcrumb scenario
Merge branch 'non-navigation-category-breadcrumbs'
Add outline to header logo
Add hover state to search button
Move skip to content link
Style focus state of header home link
Style focus/hover state of footer home link
Give mobile nav a focus & hover state and add to styleguide
Update visually hidden cookie message close text
Change homepage H1 to Money Advice Service
Fix duplicate id from cloned primary nav
Merge pull request #469 from moneyadviceservice/accessibility-fixes
Add moderniser feature detection to the HEAD
Add flexbox for modern browsers and fallback for everyone else
Rename file and move to vendor folder