Modify query_error() to log errors to a database table instead of displaying them on the screen. This should

let us more easily debug difficult or intermittent issues that users may not report. Add a cron to report logged
errors to appdb admins every night.  Implement some basic unit tests for the new error logging code

tables/create_tables

@@ -30,3 +30,5 @@ mysql -p -u root < buglinks.sql
 echo Adding monitors
 mysql -p -u root < monitors.sql
 
+echo Creating error logging tables
+mysql -p -u root < error_log.sql