Add support for GovCloud tenants

[mattcockrell]

Could you add the ability to sign in to multiple clouds? Specifically, I need to use an account in the US Gov cloud (using the login.microsoftonline.us endpoint). This would also change the TLD for most of the API calls, and a couple go to completely different domains.

[cricketthomas]

This feature should be on the way soon. Have you had a chance to use the app at all or was this a limiting factor?

The multiple accounts signed in a the same time is also something I am looking into.

[mattcockrell]

Cool, this was a partially limiting factor. I'm also experiencing an issue on startup.

It also just spins when trying to load the Subscriptions list. Those two things may be related.