Merge remote-tracking branch 'private/add-cover-detection' into AddCoverImageSupport

layouts/partials/featured.html

+{{ $linkToCover := "" }}
+{{ if .Params.featured_image }}
+    {{ $linkToCover = .Params.featured_image }}
+{{ else }}
+    {{ $img := .Resources.GetMatch "**cover*.jpg" }}
+    {{ with $img }}
+        {{ $linkToCover = .Permalink }}
+    {{ end }}
+{{ end }}
+{{ return $linkToCover }}

layouts/partials/page-header.html

-{{ $featured_image := .Params.featured_image }}
+{{ $featured_image := partial "featured.html" . }}
 {{ if $featured_image }}
   {{/* Trimming the slash and adding absURL make sure the image works no matter where our site lives */}}
   {{ $featured_image := (trim $featured_image "/") | absURL }}

layouts/partials/summary-with-image.html

-{{ $featured_image := .Params.featured_image }}
+{{ $featured_image := partial "featured.html" . }}
 <article class="bb b--black-10">
   <div class="db pv4 ph3 ph0-l no-underline dark-gray">
     <div class="flex flex-column flex-row-ns">
-      {{ if .Params.featured_image }}
+      {{ if $featured_image }}
           {{/* Trimming the slash and adding absURL make sure the image works no matter where our site lives */}}
         {{ $featured_image := (trim $featured_image "/") | absURL }}
         <div class="pr3-ns mb4 mb0-ns w-100 w-40-ns">
           </a>
         </div>
       {{ end }}
-      <div class="blah w-100{{ if .Params.featured_image }} w-60-ns pl3-ns{{ end }}">
+      <div class="blah w-100{{ if $featured_image }} w-60-ns pl3-ns{{ end }}">
         <h1 class="f3 fw1 athelas mt0 lh-title">
           <a href="{{.Permalink}}" class="color-inherit dim link">
             {{ .Title }}

layouts/post/summary-with-image.html

 <article class="bb b--black-10">
   <a class="db pv4 ph3 ph0-l no-underline dark-gray dim" href="{{ .Permalink }}">
     <div class="flex flex-column flex-row-ns">
-      {{ if .Params.featured_image }}
+      {{ $featured_image := partial "featured.html" . }}
+      {{ if $featured_image }}
         <div class="pr3-ns mb4 mb0-ns w-100 w-40-ns">
-          <img src="{{ .Params.featured_image }}" class="db" alt="image from {{ .Title }}">
+          <img src="{{ $featured_image }}" class="db" alt="image from {{ .Title }}">
         </div>
       {{ end }}
-      <div class="w-100{{ if .Params.featured_image }} w-60-ns pl3-ns{{ end }}">
+      <div class="w-100{{ if $featured_image }} w-60-ns pl3-ns{{ end }}">
         <h1 class="f3 fw1 athelas mt0 lh-title">{{ .Title }}</h1>
         <div class="f6 f5-l lh-copy nested-copy-line-height">
           {{ .Summary }}