switch back to sorting by date

this works again, possibly due to the better archiving. And as epoch
sometimes makes a bad 'find first year' result, it's better to use this.

Author: Humbedooh

site/api/stats.lua

@@ -380,7 +380,7 @@ function handle(r)
 
             sort = {
                 {
-                    epoch = {
+                    date = {
                         order = "asc"
                     }
                 }