Improve error reporting

[danrademacher]

We have a system in place that sends emails if the ETL script hits an exception.

We confirmed it worked back in March:

But then as described in #28 and #25, we have had ongoing import failures that don't cause emails to be sent. I think what we need to do is add more conditions that send emails.

Like if we see error in the API response from CARTO, we should trigger an alert:
2020-09-01T17:23:25.713549+00:00 app[scheduler.3180]: 05:23:25 PM - INFO - {"error":["You are over platform's limits: SQL query timeout error. Refactor your query before running again or contact CARTO support for more details."],"context":"limit","detail":"datasource"}

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