Support for Azure AD single-sign-on

[kierdavis]

In a similar vein to #57 and #80, it would be great to be able to use Azure Active Directory as an authentication provider.

From my (limited) experience of Azure AD this isn't a trivial thing to implement; I'm mainly just logging this issue to gauge interest.

[Hirevo]

Hello,

It's true that there is definitely some interest for alternative/external authentication methods.
I am currently thinking about ways to decouple the authentication part from the rest of the Alexandrie's code, to allow to swap them.
Maybe something resembling PassportJS could be built for Alexandrie and even as a standalone library.

Thanks for filing the issue and showing interest in this.