Favorites servers fix, one server update and show privates.

Fixed favorites servers - they now correctly added/removed in/from cache,
and also fixed favorite server edition dialog, which now also takes
advantage from server's cache.

Added new toolbar button for updating one server. It works :).

Added new column in servers lists, which shows is server is private or public.

datamodels/server.go

@@ -38,4 +38,6 @@ type Server struct {
     ExtendedConfig      string          `db:"extended_config"`
     // Players information.
     PlayersInfo         string          `db:"players_info"`
+    // Is server private?
+    IsPrivate           string          `db:"is_private"`
 }