Move cron process to foreground

- Execute checkBackgroundProcesses in background
- Execute cron process in foreground to keep the container alive
- Remove 'sleep infinity' trick in case cron is enabled

docker/files/scripts/start.sh

@@ -68,9 +68,9 @@ curl -k http://"$SITE_NAME"/API/SystemAPI?method=runPendingDatabaseUpdates
 
 # Start Cron
 if [ "$ASPEN_CRON" == "yes" ]; then
-	service cron start
 	php /usr/local/aspen-discovery/code/web/cron/checkBackgroundProcesses.php "$SITE_NAME" &
+	cron -f -L 2
+else
+/bin/bash -c "trap : TERM INT; sleep infinity & wait"
 fi
 
-# Infinite loop
-/bin/bash -c "trap : TERM INT; sleep infinity & wait"