Added + to Blog index page which links to new blog post on prose.io
Adjusted navigation and updated reference content
Merge branch 'gh-pages' into rogo-xpp

Conflicts:
	_site/assets/css/main.min.css
	_site/content/docs/guides/index.html
	_site/content/docs/principles-guide/index.html
	_site/content/docs/strategy/index.html
	_site/content/docs/tools-methods/index.html
	_site/feed.xml