Refactor github.py to work as a module

[Ianleeclark]

Essentially, I want github.py to have brothers and sisters like gitlab.py, bitbucket.py, &c., so that they can be loaded as-needed.

As it stands right now, I want github.py to only function in calling github apis with info provided. Nothing else.

It does much, much more at the moment, however.

[agentultra]

:+1: