gitweb: rss feed managingEditor

The RSS 2.0 specification allows an optional managingEditor tag for the
channel, containing the "email address for person responsible for editorial
content", which is basically the project owner.

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -6074,7 +6074,9 @@ XML
 		print "<title>$title</title>\n" .
 		      "<link>$alt_url</link>\n" .
 		      "<description>$descr</description>\n" .
-		      "<language>en</language>\n";
+		      "<language>en</language>\n" .
+		      # project owner is responsible for 'editorial' content
+		      "<managingEditor>$owner</managingEditor>\n";
 		if (defined $logo || defined $favicon) {
 			# prefer the logo to the favicon, since RSS
 			# doesn't allow both