Make logging a bit more informational

[cdegroot]

I was debugging some kafka_ex using code and noticed that what was logged wasn't really helping me. Some things I changed to help me find my coding mistake quicker:

• In terminate/2, log the reason. Nine times out of ten, termination is because of something crashing and the reason has the details;
• Log the partition when a leader is not there because leaders are per topic/partition, not per topic;
• Log the function that logs the missing leader, as there are three identical error messages and that makes it hard to figure our where in the flow things are going wrong.

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[joshuawscott]

👍