implemented means of passing in module to handle oauth callback
expecting shortstop path: style value in config to point to auth module
Merge branch 'feature-add-ability-for-koast-app-to-handle-oauth-callback' of https://github.com/HoltMansfield/koast into HoltMansfield-feature-add-ability-for-koast-app-to-handle-oauth-callback

Conflicts:
	lib/authentication/oauth.js
Merge branch 'HoltMansfield-feature-add-ability-for-koast-app-to-handle-oauth-callback'