Fix image rotation issues

Images loaded in the browser do not obey the image orientation
that is stored in the EXIF data. Firefox supports a small
CSS change that will auto-rotate the images :)

css/main.css

@@ -451,6 +451,7 @@ html.no-js .sidebar .collapsible-content {
 #content img {
   max-width:100%;
   border:1px solid #CCC;
+  image-orientation:from-image;
 }
 
 #content h4 {
@@ -776,4 +777,4 @@ video {
 
 .mentor {
   padding-bottom: 1.5em;
-}
+}