Improve blog post display

* Add a post date to each post
* Do not show the post date for tours
* Only show posts tagged "current-event" on the home page (hiding 37c3 entries)
* Use a custom template for sorting the summary list by title (instead of the default by date)

layouts/tours/list.html

@@ -1,16 +0,0 @@
-{{ define "main" -}}
-<main class="main layout__main">
-<header>
-<h1 class="title">{{ .Title }}</h1>
-</header>
-
-{{ .Content }}
-
-{{ $paginator := .Paginate (.Pages) -}}
-{{ range $paginator.Pages.ByTitle -}}
-{{ .Render "summary" }}
-{{ end -}}
-
-{{ partial "pagination.html" . }}
-</main>
-{{ end -}}