Add warn_interval

- this allows you to have a setting that will continue to trigger even
after initial trigger
- instead of trigger<->recover ping pong, you can ensure it will trigger
again so you can see if the lagtimes are going up/down over this period.
- it won't trigger in this period if lagtime is acceptable (it already recovered)
- also rm test_resque2, already moved it to test_ver_2