Review log severity levels to prevent false positives

[eulerfx]

Events get marked with a severity level such as WARN or ERROR. The severity levels assigned to events should be reviewed to be more intuitive. For example, connection errors get marked with ERROR even though from the perspective of the client as a whole, they can be considered WARN because the error is transient and will be recovered from.

One idea is to only mark an event with ERROR when no additional recovery will be attempted.

See also: #96
See also: https://github.com/jet/kafunk/wiki/FAQs#how-does-logging-work

[eulerfx]

Addressed in #213