Review the way we're handling telegram responses

[elboletaire]

Seems that, when a telegram message fails, the entire operator crashes and the entire payload of that task is moved to the dead-letter in consequence.

We should check the way telegram messages are handled, specially, when they fail.

[elboletaire]

A workaround for this could be to set allowFailure to true by default in the telegram plugin. Although I don't like too much this solution.... I think we need to rethink how the promise chain responses are returned.