Add /info page

This is only for users logged in, with granted "admin" privileges
(is_admin column in users table in database, by default false for
everybody, has to be manually changed in database).

Info page shows loaded modules, perl version and paths to used perl
interpreter and top level of explain.depesz.com application.

lib/Explain.pm

@@ -71,6 +71,9 @@ sub startup {
     # route: 'help'
     $routes->route( '/help' )->to( 'controller#help' )->name( 'help' );
 
+    # route: 'info'
+    $routes->route( '/info' )->to( 'controller#info' )->name( 'info' );
+
     return;
 }