Add crowdfunding banner to website

www/header.asciidoc

@@ -14,4 +14,7 @@
 	<a href="CONTRIBUTING.html">Contributing</a>
 	<a href="https://www.github.com/The-Compiler/qutebrowser">GitHub</a>
 </div>
+<div id="crowdfunding">
+qutebrowser is currently running a crowdfunding campaign to add support for the QtWebEngine backend, which fixes many issues. Please <a href="http://igg.me/at/qutebrowser">check it out</a>!
+</div>
 +++

www/qute.css

@@ -44,12 +44,17 @@ body {
 	color: #666666;
 }
 
+#crowdfunding {
+    padding: 10px 10px;
+    background-color: #a6dfff;
+    margin-bottom: 10px;
+}
+
 #menu {
 	padding: 0px 20px;
 	background-color: #555555;
 	color: #CCC;
 	overflow: auto;
-	margin-bottom: 10px;
 	
 	-webkit-user-select: none;
 	-moz-user-select: none;