Keepalive interval not respected

[saiello]

Setting a big value for the interval makes the keepalive to be fired continuously.

I created an example to show when the problem occurs in https://github.com/saiello/ng-idle/blob/bug/keepalive-fired-continuously/sample/keepalive.html

Open the sample page providing the query param "seconds" with a value greater than 15032385. The event counter will be incremented continuously.