Add jumbotron to single template

Doing this required making edits in lots of places; the container opened
in the header has been moved into the necessary places for the
different templates since a jumbotron inside a container will not be
full-width.

Page titles have moved to the jumbotron.

This commit adds front-matter for content: `description`, which is the
subtitle in the jumbotron.

Signed-off-by: Ethan Madison <ethan@ethanmad.com>

layouts/_default/list.html

 {{ partial "header.html" . }}
 
+<div class="container">
 <div class="row">
 	<div class="col-sm-8 doc-main">
 		<main role="main">

layouts/_default/single.html

 {{ partial "header.html" . }}
 
+<div class="jumbotron">
+    <div class="container">
+        <h1>{{ .Title }}</h1>
+        <p>{{ with .Params.description }}{{ . }}{{ end }}</p>
+    </div>
+</div>
+
+<div class="container">
 <div class="row">
 	<div class="col-sm-8 doc-main">
 		<main role="main">
 			<article>
-				<a id="title"></a>
-				<h1 class="doc-entry-title">{{ .Title }}</h1>
 				<div class="doc-entry-meta">
 					{{ if not .Params.noshowdate }}
 					<span><time datetime="{{ .Date.Format "2006-01-02" }}">{{ .Date.Format "January 02, 2006" }}</time></span>

layouts/index.html

 {{ $baseUrl := .Site.BaseURL }}
 {{ partial "header.html" . }}
 
-</div> <!-- </container> from header partial -->
-
 <main role="main">
 
-<div class="row">
-	<!-- Main jumbotron for a primary marketing message or call to action -->
-	<div class="jumbotron">
-        <div class="container">
-            <h1>{{ .Site.Title }}</h1>
-            <p>{{ if isset .Site.Params "description" }}{{ .Site.Params.description }}{{ else }}You can customize this text by params "description" in your <code>config.toml</code>.{{ end }}</p>
-        </div>
+<div class="jumbotron">
+    <div class="container">
+        <h1>{{ .Site.Title }}</h1>
+        <p>{{ if isset .Site.Params "description" }}{{ .Site.Params.description }}{{ else }}You can customize this text by params "description" in your <code>config.toml</code>.{{ end }}</p>
     </div>
 </div>
 

layouts/partials/header.html

@@ -54,5 +54,3 @@
 			</div><!--/.nav-collapse -->
 		</div>
 	</nav>
-
-<div class="container">