Consume messages from a single partition of a single Kafka topic.

Assignments are received from a group consumer member, Kaffe.GroupMember.

Messages are delegated to Kaffe.Worker. The worker is expected to cast back a response, at which time the stored offset will be acked back to Kafka.

The options (ops) to subscribe/7 may include the beginning offset using :begin_offset.

The subscriber reads the following options out of the configuration:

- `max_bytes` - The maximum number of message bytes to receive in a batch
- `min_bytes` - The minimum number of message bytes to receive in a batch
- `max_wait_time` - Maximum number of milliseconds broker will wait for `:min_bytes` of messages
    to be collected
- `offset_reset_policy` - The native `auto.offset.reset` option,
    either `:reset_to_earliest` or `:reset_to_latest`.

See: https://github.com/klarna/brucke/blob/master/src/brucke_member.erl Also: https://github.com/klarna/brod/blob/master/src/brod_consumer.erl