gitweb: Put project README in div.readme, fix its padding

Put (optional) projects README on "summary" page in <div> element
using "readme" class.  This allow to style it using CSS.

Add padding to project's README to make it line out with the rest
of the page.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>

gitweb/gitweb.css

@@ -85,6 +85,10 @@ div.title, a.title {
 	color: #000000;
 }
 
+div.readme {
+	padding: 8px;
+}
+
 a.title:hover {
 	background-color: #d9d8d1;
 }