Merge branch 'adrianbanks:add-new-dates' into staging

Add a preview and closed date to the site

Conflicts:
	DDDEastAnglia.Tests/ActionResultExtensions.cs
	DDDEastAnglia.Tests/ConferenceLoaderBuilder.cs
	DDDEastAnglia/App_Start/RouteConfig.cs
	DDDEastAnglia/Domain/Conference.cs
	DDDEastAnglia/Views/Shared/_Layout.cshtml
Add a menu linking to the old sites