long running instances

[Willyfrog]

most of the time, we create an instance to test a feature and forget to destroy after some time. Since this can happen a lot, i'd suggest a couple of options to prevent/minimize it:

• daily alert on running instances
• TTL option (i'd say with a couple of days of default) that will terminate the instance after a while. it would be great if it would issue a DM reminding that it will be destroyed some time before that happens if there is an option to extend it.