Fix #253 by providing support for Microsoft Account Login

Here it is! The BIG ONE! OAUTH! :sparkles: YAY! :sparkles: 

Fixes #253 

# Deployment Notes
1. Work with Jeff and Andrew to provision accounts for the various NuGet Environments at https://account.live.com/developers/applications
2. Update CSCFG with values for Auth.MicrosoftAccount.[Enabled/ClientID/ClientSecret] based on the data from Step 1

# Code Review Notes
... coming soon ...

# Test Notes
... coming soon ...