* 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

Implement methods to convert a Struct object to a pythonic object

Identity is not the same thing as equality in Python so use ==/!= to compare str, bytes, and int literals. In Python >= 3.8, these instances will raise __SyntaxWarnings__ so it is best to fix them now. https://docs.python.org/3.8/whatsnew/3.8.html#porting-to-python-3-8

% __python__
```
>>> consumer = "cons"
>>> consumer += "umer"
>>> consumer == "consumer"
True
>>> consumer is "consumer"
False
>>> 0 == 0.0
True
>>> 0 is 0.0
False
```