* Add consumergroup related errors
* Add DeleteGroups to protocol.admin
* Implement delete_groups feature on KafkaAdminClient

* Add logic for inferring newer broker versions

- New Fetch / ListOffsets request / response objects
- Add new test cases to inferr code based on mentioned objects
- Add unit test to check inferred version against whatever resides in KAFKA_VERSION
- Add new kafka broker versions to integration list
- Add more kafka broker versions to travis task list
- Add support for broker version 2.5 id

* Implement PR change requests: fewer versions for travis testing, remove unused older versions for inference code, remove one minor version from known server list
Do not use newly created ACL request / responses in allowed version lists, due to flexible versions enabling in kafka actually requiring a serialization protocol header update
Revert admin client file change

Previously we weren't accounting for when the response tuple also has a
`error_message` value.

Note that in Java, the error fieldname is inconsistent:
 - `CreateTopicsResponse` / `CreatePartitionsResponse` uses `topic_errors`
 - `DeleteTopicsResponse` uses `topic_error_codes`
So this updates the `CreateTopicsResponse` classes to match.

The fix is a little brittle, but should suffice for now.