remove the removeAllSubscriptions function

[Sunny-NEC]

pr for the issue #576

[fgalan]

Not sure if just removing the code is a proper solution for issue #576... Note this comment in that issue:

If my theory confirms (I may be wrong) it seems that unsubcription code in the library is dead code. As a consecuence, subscriptions are not correctly cleaned up when devices are deleted by API, leaving dirty stuff in CB.

So the solution shouldn't be remove the unsubscription code in the library but using it properly in the user code (IOTA agents code) to clean up subscriptions when devices are deleted so no "zombie" subscription remains at CB after the deletion.

[Sunny-NEC]

@fgalan I did some test but did not find any issue after removing this function.

[fgalan]

@fgalan I did some test but did not find any issue after removing this function.

Yes, but that's not the way of solving issue #576 :) The good solution is to properly use that code, not removing it. Please find my detailed comment above.