Add jumbotron images

In addition to setting a background-image, there is a drop shadow for
the text to make titles pop out and an inset shadow to separate the
jumbotron from the main section below it.

Close #3.
Signed-off-by: Ethan Madison <ethan@ethanmad.com>

layouts/partials/jumbotron.html

 {{ $isHomePage := eq .Title .Site.Title }}
 
-<div class="jumbotron">
+<div class="jumbotron" style="background-image: url({{ if $isHomePage }}{{ with .Site.Params.image }}{{ . }}{{ end }}{{ else }}{{ with .Params.image }}{{ . }}{{ end }}{{ end }})">
     <div class="container">
         <h1>{{ if $isHomePage }}{{ .Site.Title }}{{ else }}{{ .Title }}{{ end }}</h1>
         <p>{{ if $isHomePage }}{{ with .Site.Params.description }}{{ . }}{{ end }}{{ else }}{{ with .Params.description }}{{ . }}{{ end }}{{ end }}</p>

static/css/bootie-docs.css

@@ -21,7 +21,6 @@ h6, .h6 {
 
 h1, .h1,
 h2, .h2 {
-  border-bottom: 1px solid #eee;
   margin-bottom: 15px;
 }
 
@@ -48,10 +47,24 @@ pre code {
   }
 }
 
+
 /*
- * Header navbar
+ * Jumbotron
  */
 
+.jumbotron {
+    margin-bottom: 10px;
+    position: relative;
+    top: -20px;
+    background-position: 0% 0%;
+    height: 350px;
+    background-size: cover;
+    background-repeat: no-repeat;
+    color: white;
+    text-shadow: #444 0 2px 1px;
+    z-index: -1;
+    box-shadow: 0 -8px 16px -4px black inset;
+}
 /*
  * Main column and sidebar layout
  */
@@ -107,6 +120,7 @@ ul.doc-list-category > li > ul > li {
 
 .doc-main h2 {
     padding-top: 15px;
+    border-bottom: 1px solid #eee;
 }
 
 .doc-main h3 {