Multi tenant validation

[Nodashi]

Hi,

thanks for this package. However a thing is missing. I am unable to validate multitenant application. It would be great if we can configure multiple tenant in the configuration to validate issuer. You can have a look to the followings links :

• https://stackoverflow.com/questions/52347821/azure-ad-multi-tenant-applications-how-to-implement-token-validation

The simplest way should be to let the user to override the _validateIssuer function

Best regards

[b1rken]

This is very much needed :)