Allow change to address version

[ambethia]

What current issue(s) does this address?, or what feature is it adding?

Address version is hard coded to 23, but is intended to be configurable in protocol.json.

I'm working with a neo fork that uses a different address version.

How did you solve this problem?

Added a variable ADDRESS_VERSION to Helper module that can be overridden.

How did you make sure your solution works?

I added a unit test to demonstrate.

Did you add any tests?

Of course!

Are there any special changes in the code that we should be aware of?

I'll be opening a PR for neo-python that updates this from Settings/protocol.json

[localhuman]

Looks like pycodestyle is unhappy

[metachris]

Looks good, thanks 👍

Just the code style has one minor issue, you can see it by running make lint. Please fix it, then i'll merge and create a new release so you can use it with neo-python.

[coveralls]

Coverage remained the same at 100.0% when pulling b69306f on ambethia:master into a0939eb on CityOfZion:master.

[coveralls]

Coverage remained the same at 100.0% when pulling b69306f on ambethia:master into a0939eb on CityOfZion:master.

[metachris]

ty 👍