add a .bigtable tr:hover css selector to visually clue in user which job row they are on in a view

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@30904 71c3de6d-444a-0410-be80-ed276b4c234a

war/resources/css/style.css

@@ -327,6 +327,10 @@ th.pane {
   padding: 3px 4px 3px 4px;
 }
 
+.bigtable tr:hover {
+  background-color: #f0f0f0;
+}
+
 .bigtable th {
   font-weight: bold;
   border: none;