tap-agent can't recover after aggregator fails for a while

[aasseman]

We observed this while the E&N aggregator had the wrong signer key set, and therefore was refusing to aggregate our receipts.
tap-agent tries a few times, then stops sending HTTP requests to the aggregator altogether until tap-agent is restarted.

[gusinacio]

List of events:

• It retrieves all the receipts
  • checks pass
  • request a rav
  • The rav fails
• It retrieves the receipts again
  • now all but one receipt failed the checks
  • all receipts are stored as invalid
  • the rav fails
• From this time on, all receipts fail and we have a different failure tracked on Store invalid receipts even if there are no valid ones in batch #214