Bug/693 ontimeinterval subscription recovery

Fixed the bug of issue #693.

This fix will probably also solve the mysterious case of 'false leaks' we've been seeing (and trying to fix).

Instead of creating a vector of subscriptions, a callback function (treating the subscription) is sent to the function that loops over the subscriptions.

The bug in the previous implementation was that the vector got corrupted as soon as the function that created the vector finished (symptom telling us we had stuff on the stack - in this case the BSON objects inside the vector).