Add warning when upgrading a townhall before buildings are upgraded

It seems like there are quite few people that are rushed, and don't realize how much it hurts them until they are th9 and someone explains to them how looting rules work. By then they don't want to start over, and its painful to catch up. They also might just drop the game.

I feel it would be helpful to show a stat, at least private to the client of their progress in their current townhall. The stat would show how many buildings upgrades remain, or something similar. If that stat is below a certain threshold when the user tries to upgrade their TH, a warning would pop up possibly explaining game play, especially looting rules.

There are probably quite a few young people or just people in general that start playing the game and do no or little research about the game to learn this on their own. Then fewer clans want them as a th8 or th9 with th6 troops and defenses.