provider nodes are sometimes not really deleted

Added some logging to debug and could not catch any exceptions or errors. I am assuming that the API is sending the `destroy()` call to the provider and the provider is failing to comply.

The libcloud API returns a boolean to detect correct deletion of a node, and mita does not check for this, so the initial fix (other than extra logging) should be to check for the response back and raise if the node fails to get removed