Register test app in Azure

[jstaf]

While looking into #107 (was looking into shared items/sharepoint support while planning things out for #70), I noticed we currently don't really request any Sharepoint permissions so the app can't enumerate the different Sharepoint libraries/drives a user has access to.

Before I start playing around with permissions, it would be good to create a "dev" copy of the app in AAD so that we can muck about with test permissions without affecting the app registration that people actually use right now.

Obviously requires #212 so we can configure the app to pick an alternate app ID.