Notify moderators when a user reaches TL3

Fonctionnalité
22

Would probably make more sense if it returned something other than 500.

In my logs I got

ActionView::Template::Error (Discourse::InvalidAccess)
/var/www/discourse/lib/auth/default_current_user_provider.rb:79:in `current_user'
1 « J'aime »
23

Added on my list to look into. :memo:

5 « J'aime »
24

Improved error message via:

4 « J'aime »