Custom Auth setup for connecting to GitHub

[sam-huckaby]

An OAuth2 Client should handle more than just general cases. It should also offer convenience methods that work out of the box for services that operate in expected and well-documented ways.

This issue is to build a new submodule for GitHub

[sam-huckaby]

I think roughly we just need to do the following:

• A GitHub config struct
• Create URL for the developer to put in a button
• Create a token exchange method