Checks after downtime#1410

Currently , there is an option to determine the monitor interval starting from 30 seconds.
With this , let us say we choose the interval as 30 minutes , then the Robot checks the site in the first 30 minutes, then in the next interval , it checks for the site response.
So, the outage is 30 minutes in this case, even if the site was back up in less than 5 minutes.

We should have an option :

1. Check the website with the specified interval (say 30 minutes).
2. If down, check the site every 5 minutes and send notification if the site is back up.