hgweb: show full date in rfc822 format in tooltips at shortlog page

hgweb: show full date in rfc822 format in tooltips at shortlog page

The absolute date was not shown anywhere in the log view for users with
enabled JavaScript.

--- a/mercurial/templates/static/mercurial.js	Sun Aug 04 16:19:12 2013 -0500
+++ b/mercurial/templates/static/mercurial.js	Sun Jun 30 11:48:21 2013 +0400
@@ -258,6 +258,7 @@
 					// We want both: date + (age)
 					node.textContent += ' ('+agevalue+')';
 				} else {
+					node.title = node.textContent;
 					node.textContent = agevalue;
 				}
 			}