Slow down LndHub auth requests in task

lib/tasks/lndhub.rake

@@ -14,6 +14,7 @@ namespace :lndhub do
       data = lndhub.balance(auth_token)
       balance = data["BTC"]["AvailableBalance"] rescue nil
       puts "#{user.address}: #{balance}" if balance && balance > 0
+      sleep 0.5
     end
   end
 end